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<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
<title><![CDATA[Досрочно завершим!]]></title>
<link href="http://odobenus.github.io/atom.xml" rel="self"/>
<link href="http://odobenus.github.io/"/>
<updated>2014-01-24T19:05:06+04:00</updated>
<id>http://odobenus.github.io/</id>
<author>
<name><![CDATA[Alexey Kishkin]]></name>
</author>
<generator uri="http://octopress.org/">Octopress</generator>
<entry>
<title type="html"><![CDATA[Переезд сайта]]></title>
<link href="http://odobenus.github.io/blog/2013/04/28/pierieiezd-saita/"/>
<updated>2013-04-28T01:15:00+04:00</updated>
<id>http://odobenus.github.io/blog/2013/04/28/pierieiezd-saita</id>
<content type="html"><![CDATA[<p>Сайт переехал на новую платформу. Вопросы, предложения можно тут в комментариях.</p>
<!-- 18139636.883344074.1367097431.2306994b1c77377645403f5e999b9cf3 -->
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[ProblemK, Алгоритм и структуры данных]]></title>
<link href="http://odobenus.github.io/blog/2011/03/29/problemk/"/>
<updated>2011-03-29T00:00:00+04:00</updated>
<id>http://odobenus.github.io/blog/2011/03/29/problemk</id>
<content type="html"><![CDATA[<p>Типовой способ расчета электронной таблицы заключается в том, что в
памяти строится таблица, содержащая выражения ячеек, а затем все эти
ячейки рекурсивно вычисляются. То есть, если ячейка A1 ссылается на
другую (скажем, C2), чтобы получить значение C2 из поцедуры вычисления
A2 вызывается вычисление C2.</p>
<p>Несмотря на все достоинства, у такого метода есть очевидные
недостатки.</p>
<!-- more -->
<ul>
<li>Циклические ссылки представляют проблему. Поэтому при расчетах
требуются дополнительные усилия, чтобы либо отмечать ячейки, которые
сейчас в состоянии расчета, либо вести определенный лог, в котором
перечичслены ячейкм в состоянии расчета.</li>
<li>Такой подход трудно масштабировать. Предполагается, что вся таблица
должна быть в памяти и доступна в любой момент.</li>
</ul>
<p>Я предполагаю использовать другой подход, который на мой взгляд проще
для восприятия и сопровождения. Идея простая – мы пытаемся вычислить
ячейки в том порядке, в котором нам их поставляет парсер. И если не
хватает зависимостей, чтобы вычислить ячейку – мы просто откладываем
ее вычисление на “попозже”.</p>
<p>То есть алгоритм такой</p>
<ul>
<li>парсер при разборе заносит все выражения ячеек в определенную
очередь</li>
<li>вычислитель пробует вычислить первую ячейку из очереди.</li>
<li>если удалось, ее значение помещается в valuecache, а сама ячейка
удаляется из очереди.</li>
<li>если не удалось – эта ячейка помещается в конец очереди.</li>
<li>когда очередь станет пустой – это значит вся таблица рассчитана,
можно начинать ее печатать.</li>
<li>В случае циклических зависимостей или нереальных ссылок (например за
границы таблицы) в очереди образуется <em>сухой остаток</em> – ячейки которые
невозможно рассчитать в принципе. Мы их просто переносим в valuecache
со значением {error, badref};</li>
<li>Чтобы узнать, что остались только нерешаемые ячейки в очереди, будем вести
счетчик подряд неудачных вычислений (который сбрасывается при любом удачном
вычислении). Если этот счетчик больше чем длина очереди – значит мы просто
тасуем нерешаемые ячейки.</li>
</ul>
<p>Тогда складывается такой набор модулей:</p>
<h2>Модули</h2>
<p><img src="https://lh4.googleusercontent.com/_qBKy8gbHL84/TZE_bksgyOI/AAAAAAAABz8/FsGvv_IhhJ8/s800/modules.png"></p>
<ul>
<li><strong>Главный модуль</strong>, содержит start point</li>
<li><strong>parser</strong> считывает <em>stdin</em> и делает разбор таблицы и ячеек в
внутреннюю форму. Результат помещается в “трубу”</li>
<li><strong>solver</strong> вычисляет значения ячеек из “трубы” и помещает значения ячеек
в valuecache. Разруливает зависимости ячеек.</li>
<li><strong>print</strong> выводит простыню в stdout из valuecache.</li>
<li><strong>machine</strong> вычисление выражений ячеек</li>
<li><strong>cell</strong> управляет <em>внешним видом</em> ячеек. То есть – как они должны
выглядеть в выводе, как должны собираться/разбираться ссылки на
ячейки.</li>
<li><strong>valuecache</strong> хранит значения (только значения, никаких формул),
ячеек. Простое KV storage</li>
<li><strong>pipe</strong> “труба” применяемая для разруливания порядка расчетов
ячеек, это по натуре queue</li>
</ul>
<h2>Достоинства такого алгоритма</h2>
<ul>
<li>Легко масштабируется по памяти – интерфейс valuecache и pipe
простые, реализация скрыта, ничто не мешает при необходимости
переписать valuecache чтобы он использовал, скажем, nosql для
сохранения данных, Или к примеру использовать AMQP для очереди. При
этом остальная часть программы, естественно, остается неихменной.</li>
<li>Легко масштабируется по процессам/процессорам. Для этого надо всего
лишь <del>выполнить</del> <del>партиц</del>. <del>партишн.</del>
распилить очередь по числу процессов, и дать каждому процессу по его
куску очереди. А когда они все завершат работу, собрать нерешаемые
ячейки из этих очередей в одну и пройтись еще раз по ней решателем.</li>
<li>Легко отлаживается – сам алгоритм простой и занимает полстраницы
кода, модули имеют минимум зависимостей и ясные интерфейсы (что
позволяет их эфективно проверять с помощью unit тестов),</li>
<li>Не имеет в своем составе холестерина</li>
</ul>
<h2>Недостатки</h2>
<ul>
<li>Скорость должна быть ниже, чем в случае рекурсивного
решателя. Потому, что некоторые ячейки придется считать несколько раз.</li>
<li>Этот алгоритм удобен только для пакетной обработки.</li>
</ul>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[watcom vs gcc]]></title>
<link href="http://odobenus.github.io/blog/2009/06/29/watcom-vs-gcc/"/>
<updated>2009-06-29T00:00:00+05:00</updated>
<id>http://odobenus.github.io/blog/2009/06/29/watcom-vs-gcc</id>
<content type="html"><![CDATA[<p>Для удовлетворения любопытства, скачал openwatcom 1.8 (такой бывший когда то
известным компилятор c/c++), исходники под линукс. собрал, и попробовал
тестовую задачку, <a href="http://shootout.alioth.debian.org/u32q/benchmark.php?test=binarytrees&lang=gcc&box=1">вот эту вот</a></p>
<p>Резуьтаты:</p>
<!-- more -->
<p>GCC</p>
<blockquote><p>walrus@home:/home/walrus/sandbox$ gcc btr.c -O3 -o btr_gcc -lm<br/>walrus@home:/home/walrus/sandbox$ time ./btr_gcc 20<br/>stretch tree of depth 21 check: -1<br/>2097152 trees of depth 4 check: -2097152<br/>524288 trees of depth 6 check: -524288<br/>131072 trees of depth 8 check: -131072<br/>32768 trees of depth 10 check: -32768<br/>8192 trees of depth 12 check: -8192<br/>2048 trees of depth 14 check: -2048<br/>512 trees of depth 16 check: -512<br/>128 trees of depth 18 check: -128<br/>32 trees of depth 20 check: -32<br/>long lived tree of depth 20 check: -1</p><p>real 1m2.138s<br/>user 1m1.852s<br/>sys 0m0.120s</p></blockquote>
<p>Watcom</p>
<blockquote><p>walrus@home:/home/walrus/sandbox$ PATH=$PATH:/opt/watcom/binl WATCOM=/opt/watcom owcc -I/opt/watcom/h -O3 -obtr_wc btr.c <br/>walrus@home:/home/walrus/sandbox$ time ./btr_wc 20<br/>stretch tree of depth 21 check: -1<br/>2097152 trees of depth 4 check: -2097152<br/>524288 trees of depth 6 check: -524288<br/>131072 trees of depth 8 check: -131072<br/>32768 trees of depth 10 check: -32768<br/>8192 trees of depth 12 check: -8192<br/>2048 trees of depth 14 check: -2048<br/>512 trees of depth 16 check: -512<br/>128 trees of depth 18 check: -128<br/>32 trees of depth 20 check: -32<br/>long lived tree of depth 20 check: -1</p><p>real 0m47.934s<br/>user 0m47.675s<br/>sys 0m0.136s</p></blockquote>
<p>62 секунды против 48 в пользу watcom-а. Ай да старик watcom!! Вот это
да!</p>
<p><strong>UPD</strong> Да, забыл – ubuntu 9.04 32 AMD, 4000+, gcc gcc версия 4.3.3 (Ubuntu 4.3.3-5ubuntu4), watcom :</p>
<blockquote><p>owcc -v
Open Watcom C/C++32 Compiler Driver Program Version 1.8beta1 LA
Portions Copyright © 1988-2002 Sybase, Inc. All Rights Reserved.
Source code is available under the Sybase Open Watcom Public License.
See <a href="http://www.openwatcom.org/">http://www.openwatcom.org/</a> for details.</p></blockquote>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[couchdb benchmark II]]></title>
<link href="http://odobenus.github.io/blog/2008/09/05/couchdb-benchmark-ii/"/>
<updated>2008-09-05T00:00:00+05:00</updated>
<id>http://odobenus.github.io/blog/2008/09/05/couchdb-benchmark-ii</id>
<content type="html"><![CDATA[<p>Однако не все так плохо..</p>
<p>Если запустить 50 программ, каждая из которых пытается вставить по 200 записей
(те же 10000 записей, что и в прошлом тесте), то вставка всех записей
укладывается в 220 сек. Значит – суммарно скорость вставки при 50 процессах –
45 записей в секунду.</p>
<p>Кстати – база couchdb с 10000 записями (структура в предыдущем сообшении блога) занимает 54.3M.</p>
<p>На компьютере Intel 3.2GHz, RAM 1G, ubuntu 8.04</p>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[couchdb benchmark еще раз]]></title>
<link href="http://odobenus.github.io/blog/2008/09/05/couchdb-benchmark/"/>
<updated>2008-09-05T00:00:00+05:00</updated>
<id>http://odobenus.github.io/blog/2008/09/05/couchdb-benchmark</id>
<content type="html"><![CDATA[<p>Попробоавл тот же тест, но 10 процессов по 10000 записей. Суммарные цифры –
100_000 записей за 2308 сек. То есть 43 записи/сек. Примерно так же как и в
прошлом тесте. Похоже, быстрее уде не разогнать.</p>
<p>Размер базы при 100000 записях – 0.6G</p>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[couchdb benchmark]]></title>
<link href="http://odobenus.github.io/blog/2008/09/04/couchdb-benchmark/"/>
<updated>2008-09-04T00:00:00+05:00</updated>
<id>http://odobenus.github.io/blog/2008/09/04/couchdb-benchmark</id>
<content type="html"><![CDATA[<p>Захотелось попробовать новую couchdb. Выглядит она хорошо, и все
сделано удобно. Однако прежде чем ее использовать в каком-нибудь
проекте, хотелось бы оценит ее возможности более точно.</p>
<p>Прежде всего посмотрим скорострельность. Для этого напишем мелкую
программу на питоне, которая вставляет ну.. 10000 записей. и пусть
пишет сколько секунд прошло с начала теста.</p>
<!-- more -->
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
<span class='line-number'>7</span>
<span class='line-number'>8</span>
<span class='line-number'>9</span>
<span class='line-number'>10</span>
<span class='line-number'>11</span>
<span class='line-number'>12</span>
<span class='line-number'>13</span>
<span class='line-number'>14</span>
<span class='line-number'>15</span>
<span class='line-number'>16</span>
<span class='line-number'>17</span>
<span class='line-number'>18</span>
</pre></td><td class='code'><pre><code class='python'><span class='line'><span class="kn">from</span> <span class="nn">couchdb</span> <span class="kn">import</span> <span class="n">Server</span>
</span><span class='line'><span class="kn">import</span> <span class="nn">time</span>
</span><span class='line'>
</span><span class='line'><span class="n">server</span> <span class="o">=</span> <span class="n">Server</span><span class="p">(</span><span class="s">'http://localhost:5984/'</span><span class="p">)</span>
</span><span class='line'><span class="k">del</span> <span class="n">server</span><span class="p">[</span><span class="s">'benchmark'</span><span class="p">]</span>
</span><span class='line'>
</span><span class='line'><span class="n">db</span> <span class="o">=</span> <span class="n">server</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="s">'benchmark'</span><span class="p">)</span>
</span><span class='line'><span class="n">benchstart</span> <span class="o">=</span> <span class="nb">int</span><span class="p">(</span><span class="n">time</span><span class="o">.</span><span class="n">time</span><span class="p">())</span>
</span><span class='line'><span class="k">print</span> <span class="s">"Begin test </span><span class="si">%s</span><span class="s">"</span><span class="o">%</span><span class="n">benchstart</span>
</span><span class='line'><span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span><span class="mi">10000</span><span class="p">):</span>
</span><span class='line'> <span class="n">doc_id</span> <span class="o">=</span> <span class="n">db</span><span class="o">.</span><span class="n">create</span><span class="p">({</span><span class="s">'type'</span><span class="p">:</span> <span class="s">'BenchRecord'</span><span class="p">,</span> <span class="s">'intfld'</span><span class="p">:</span> <span class="n">i</span><span class="p">,</span> <span class="s">'charfld'</span><span class="p">:</span> <span class="s">'SomeName</span><span class="si">%s</span><span class="s">'</span><span class="o">%</span><span class="n">i</span> <span class="p">})</span>
</span><span class='line'> <span class="k">if</span> <span class="n">i</span> <span class="o">%</span> <span class="mi">100</span> <span class="o">==</span> <span class="mi">0</span><span class="p">:</span>
</span><span class='line'><span class="c"># print "%s :: %s "%(datetime.datetime.today(),i)</span>
</span><span class='line'> <span class="n">bench_offset</span> <span class="o">=</span> <span class="nb">int</span><span class="p">(</span><span class="n">time</span><span class="o">.</span><span class="n">time</span><span class="p">())</span> <span class="o">-</span> <span class="n">benchstart</span>
</span><span class='line'> <span class="k">print</span> <span class="s">"</span><span class="si">%d</span><span class="se">\t</span><span class="si">%d</span><span class="s"> "</span><span class="o">%</span><span class="p">(</span><span class="n">bench_offset</span><span class="p">,</span><span class="n">i</span><span class="p">)</span>
</span><span class='line'>
</span><span class='line'><span class="k">print</span> <span class="s">"End test, </span><span class="si">%d</span><span class="s"> sec"</span><span class="o">%</span><span class="p">(</span><span class="nb">int</span><span class="p">(</span><span class="n">time</span><span class="o">.</span><span class="n">time</span><span class="p">())</span> <span class="o">-</span> <span class="n">benchstart</span><span class="p">)</span>
</span><span class='line'><span class="k">del</span> <span class="n">server</span><span class="p">[</span><span class="s">'benchmark'</span><span class="p">]</span>
</span></code></pre></td></tr></table></div></figure>
<p>Запускаем – получили в результате:</p>
<blockquote><p>Begin test 1220531930<br/>6 100 <br/>11 200 <br/>17 300 <br/>23 400 <br/>29 500 <br/>35 600 <br/>40 700 <br/>46 800 <br/>52 900 <br/>58 1000 <br/>64 1100 <br/>70 1200 <br/>76 1300 <br/>82 1400 <br/>87 1500 <br/>93 1600 <br/>99 1700 <br/>105 1800 <br/>111 1900 <br/>117 2000 <br/>123 2100 <br/>129 2200 <br/>135 2300 <br/>140 2400 <br/>146 2500 <br/>152 2600 <br/>158 2700 <br/>164 2800 <br/>170 2900 <br/>176 3000 <br/>182 3100 <br/>188 3200 <br/>194 3300 <br/>200 3400 <br/>206 3500 <br/>212 3600 <br/>218 3700 <br/>224 3800 <br/>229 3900 <br/>235 4000 <br/>241 4100 <br/>247 4200 <br/>254 4300 <br/>260 4400 <br/>266 4500 <br/>272 4600 <br/>278 4700 <br/>284 4800 <br/>290 4900 <br/>296 5000 <br/>302 5100 <br/>309 5200 <br/>315 5300 <br/>321 5400 <br/>327 5500 <br/>333 5600 <br/>339 5700 <br/>345 5800 <br/>351 5900 <br/>357 6000 <br/>363 6100 <br/>369 6200 <br/>376 6300 <br/>382 6400 <br/>388 6500 <br/>394 6600 <br/>400 6700 <br/>406 6800 <br/>412 6900 <br/>418 7000 <br/>424 7100 <br/>430 7200 <br/>436 7300 <br/>442 7400 <br/>448 7500 <br/>454 7600 <br/>460 7700 <br/>466 7800 <br/>472 7900 <br/>478 8000 <br/>484 8100 <br/>490 8200 <br/>496 8300 <br/>502 8400 <br/>508 8500 <br/>514 8600 <br/>520 8700 <br/>526 8800 <br/>532 8900 <br/>538 9000 <br/>544 9100 <br/>550 9200 <br/>556 9300 <br/>562 9400 <br/>568 9500 <br/>574 9600 <br/>580 9700 <br/>587 9800 <br/>593 9900 <br/>End test, 599 sec</p></blockquote>
<p>Отсюда мораль.</p>
<ol>
<li>Вставка 100 записей за (в среднем) 6 секунд. Немного. 16 записей/сек</li>
<li>достаточно линейно , в диапазоне до 10000 записей.</li>
</ol>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[Превращение]]></title>
<link href="http://odobenus.github.io/blog/2008/08/16/turnout/"/>
<updated>2008-08-16T00:00:00+05:00</updated>
<id>http://odobenus.github.io/blog/2008/08/16/turnout</id>
<content type="html"><![CDATA[<p><embed src="http://www.myheritagefiles.com/video/L/28/nsxi84_7016384a8d6a84wpi7kt84" width="340" height="340" type="application/x-shockwave-flash" wmode="transparent"/></p>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[Марк Твен]]></title>
<link href="http://odobenus.github.io/blog/2008/06/22/mark-twain/"/>
<updated>2008-06-22T00:00:00+05:00</updated>
<id>http://odobenus.github.io/blog/2008/06/22/mark-twain</id>
<content type="html"><![CDATA[<blockquote><p>“Если вам понадобится подвергнуть молодого человека тяжелому и мучительному
наказанию, возьмите с него слово, что он в течение года будет вести дневник.”</p></blockquote>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[erlang & postgresql auth]]></title>
<link href="http://odobenus.github.io/blog/2008/06/06/erlang-postgresql-auth/"/>
<updated>2008-06-06T00:00:00+05:00</updated>
<id>http://odobenus.github.io/blog/2008/06/06/erlang-postgresql-auth</id>
<content type="html"><![CDATA[<p>Для прямого доступа из эрланга в postgresql (минуя odbc) есть хорошая библиотечка, написанная Martin Carlsson из Erlang Training & Consulting ltd
<a href="http://erlang-consulting.com/aboutus/opensource.html">Здесь</a>.</p>
<p>У нее есть один недостаток – она рассчитана только на md5 authentication в постгресе.</p>
<p>Если приложение разрабатывается с нуля, то md5 auth – не представляет проблемы, как захотим, так и настроим, но в нашем случае уже есть
большой и толстый postgresql сервер, со своими админами и правилами выделения учетных записей. В этом сервере метод доступа у большинства аккаунтов –
password. И никак это не поправишь. В отличие от технических проблем – административные проблемы плохо поддаются решению..</p>
<p>Пришлось прочитать хорошенько документацию postgresql, раздел где описан протокол, и поправить erlang-овскую библиотеку.
Вот, чтобы не забыть, что я там наисправлял, и<br/>
выкладываю diff</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
<span class='line-number'>7</span>
<span class='line-number'>8</span>
<span class='line-number'>9</span>
<span class='line-number'>10</span>
<span class='line-number'>11</span>
<span class='line-number'>12</span>
<span class='line-number'>13</span>
<span class='line-number'>14</span>
<span class='line-number'>15</span>
<span class='line-number'>16</span>
</pre></td><td class='code'><pre><code class='diff'><span class='line'><span class="gh">diff -Naur oldsrc/psql_logic.erl src/psql_logic.erl</span>
</span><span class='line'><span class="gd">--- oldsrc/psql_logic.erl 2006-09-18 17:46:20.000000000 +0200</span>
</span><span class='line'><span class="gi">+++ src/psql_logic.erl 2008-03-12 17:41:48.000000000 +0100</span>
</span><span class='line'><span class="gu">@@ -139,6 +139,12 @@</span>
</span><span class='line'> AuthDigest = psql_protocol:md5digest(State#state.digest, Salt),
</span><span class='line'> psql_connection:command(State#state.connection, {send, AuthDigest}),
</span><span class='line'> {next_state, authentication, State};
</span><span class='line'><span class="gi">+</span>
</span><span class='line'><span class="gi">+authentication({psql, authentication, <<0,0,0,3>>}, State) -></span>
</span><span class='line'><span class="gi">+ CTPassw = psql_protocol:ctpasswd(State#state.password),</span>
</span><span class='line'><span class="gi">+ psql_connection:command(State#state.connection, {send, CTPassw}),</span>
</span><span class='line'><span class="gi">+ {next_state, authentication, State};</span>
</span><span class='line'><span class="gi">+</span>
</span><span class='line'>authentication({psql, authentication, <<0,0,0,0>>}, State) ->
</span><span class='line'> {next_state, setup, State};
</span><span class='line'>authentication({psql, error, Error}, State) ->
</span></code></pre></td></tr></table></div></figure>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
<span class='line-number'>7</span>
<span class='line-number'>8</span>
<span class='line-number'>9</span>
<span class='line-number'>10</span>
<span class='line-number'>11</span>
<span class='line-number'>12</span>
<span class='line-number'>13</span>
<span class='line-number'>14</span>
<span class='line-number'>15</span>
<span class='line-number'>16</span>
<span class='line-number'>17</span>
<span class='line-number'>18</span>
<span class='line-number'>19</span>
<span class='line-number'>20</span>
<span class='line-number'>21</span>
</pre></td><td class='code'><pre><code class='diff'><span class='line'><span class="gd">--- oldsrc/psql_protocol.erl 2006-09-18 17:46:24.000000000 +0200</span>
</span><span class='line'><span class="gi">+++ src/psql_protocol.erl 2008-03-12 17:41:31.000000000 +0100</span>
</span><span class='line'><span class="gu">@@ -21,7 +21,7 @@</span>
</span><span class='line'> to_string/1]).
</span><span class='line'>
</span><span class='line'> -export([authenticate/4,
</span><span class='line'><span class="gd">- md5digest/2,</span>
</span><span class='line'><span class="gi">+ md5digest/2,ctpasswd/1,</span>
</span><span class='line'> copy_done/0,
</span><span class='line'> q/1]).
</span><span class='line'>
</span><span class='line'><span class="gu">@@ -65,6 +65,9 @@</span>
</span><span class='line'> Auth = md5([Digest, Salt]),
</span><span class='line'> {password_message, <<"md5", Auth/binary, 0:8>>}.
</span><span class='line'>
</span><span class='line'><span class="gi">+ctpasswd(Passw) -></span>
</span><span class='line'><span class="gi">+ PB = list_to_binary(Passw),</span>
</span><span class='line'><span class="gi">+ {password_message, << PB/binary,0:8 >>}.</span>
</span><span class='line'><span class="gi">+</span>
</span><span class='line'>copy_done() ->
</span><span class='line'> {'copy_done', []}.
</span></code></pre></td></tr></table></div></figure>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[erlang snmp client]]></title>
<link href="http://odobenus.github.io/blog/2008/03/11/erlang-snmp-client/"/>
<updated>2008-03-11T00:00:00+04:00</updated>
<id>http://odobenus.github.io/blog/2008/03/11/erlang-snmp-client</id>
<content type="html"><![CDATA[<p>Вот понадобилось опрашивать некоторые железные switch через snmp из erlang.
Первая попытка понять что для этого нужна (наскоком, по Буденновски) – не удалась. На erlang.org полно документации
как писать и управлять snmp сервера, но вот информация по клиентам – разбросана по крупицам.</p>
<!-- more -->
<p></p>
<p>Так что пришлось собраться и создать картину у себя в голове, как должен выглядить snmp клиент.</p>
<h2>Общая картина</h2>
<p><img src="http://odobenus.github.io/images/snmp_blog.png"></p>
<p>Общая идея такая. Нет одной такой командочки типа snmpwalk. Мы вынуждены строить целую систему для того чтобы опросить
железку.</p>
<p>Есть snmp manager, мы его должны настроить и запустить, даже если у нас только клиент. Этот snmp manager содержит
список snmp user. Я сначала думал что snmp user – это что-то типа community, оказалось – нет.. Snmp user в erlang –
это такой <em>модуль</em>, который содержит просто набор callback для приема ответов от устройств.</p>
<p>Manager должен либо определять этого user-а в свой конфигурации, либо зарегистрировать его с помощью
<code>snmpm:register_user(имя, модуль).</code></p>
<p>Дальше нам нужны agents. То есть manager каждому такому user назначает (в конфиге, либо с помощью <code>snmpm:register_agent</code> )
набор агентов которых опрашивать. Вот эти агенты как раз и содержат реквизиты опрашиваемых железок. Там, IP, community, port,
версию протокола и т.д.</p>
<p>Когда все это настроено, можно посылать из manager-а запрос. Например с помощью <code>snmpm:ag()</code>. Manager поищет в настройках который это агент(по адресу).
Пошлет асинхронный запрос на железку, а когда придет ответ, Manager по привязанным user/agent, сообразит на которого
user (ну грубо говоря в какой модуль) его переслать.</p>
<p>В данном случает придет ответ на <code>handle_pdu(Addr, Port, ReqId, SnmpResponse, UserData)</code> в том user-е к которому привязан агент, куда посылался запрос.</p>
<p>В следующих постах приведу примеры кода.</p>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[Performance degradation for gcc]]></title>
<link href="http://odobenus.github.io/blog/2008/02/29/performance-degradation-for-gcc/"/>
<updated>2008-02-29T00:00:00+04:00</updated>
<id>http://odobenus.github.io/blog/2008/02/29/performance-degradation-for-gcc</id>
<content type="html"><![CDATA[<p>Просмативая свои старые архивы, нашел мелкую программу sieve – решето
Эратосфена, которая была написана на разных языках. И там же валялся бинарник
этой программы, скомпилированной gcc в далеком (по моему 2002) году. Запустил
из интереса – получилось</p>
<!-- more -->
<blockquote><p>103763 iterations in 10.000000 seconds.</p></blockquote>
<p>Скомпилировал текущей версией gcc из ubuntu – получилось</p>
<blockquote><p>96992 iterations in 10.000000 seconds</p></blockquote>
<p>Вот тебе бабушка и Юрьев день! Какой был в 2002 gcc не помню, file a.out покзывает</p>
<blockquote><p>a.out: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), for GNU/Linux 2.0.0,
dynamically linked (uses shared libs), not stripped</p></blockquote>
<p>Теперь у нас gcc version 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2), file
показывает</p>
<blockquote><p>a.out: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), for GNU/Linux 2.6.8,
dynamically linked (uses shared libs), not stripped</p></blockquote>
<p>То есть все честно.. Но медленнее..</p>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[Standalone connection pool]]></title>
<link href="http://odobenus.github.io/blog/2008/02/08/standalone-connection-pool/"/>
<updated>2008-02-08T00:00:00+04:00</updated>
<id>http://odobenus.github.io/blog/2008/02/08/standalone-connection-pool</id>
<content type="html"><![CDATA[<p>В одном из проектов на яве мне понадобился connection pool, без него
соединения с базой получались слишком частые. После определенного
поиска обнаружил DBCP от apache и
<a href="http://forum.vingrad.ru/sources/topic-157958.html">статью на винграде</a></p>
<p>DBCP мне не очень понравился, дело вкуса, конечно, но слишком много
зависимостей. Да и тяжеловат он для мелкого проекта. Vingrad-овский
connection pool – делает немного не то что хотелось кэширует
statements.. И отсутствует обработка случаев, когда, к примеру база
умрет (на время)..</p>
<p>Критика без конкретных предложений – критиканство. Так что взял и
написал как нравится самому. Вот что получилось:</p>
<!-- more -->
<h2>Итак. Общая идея</h2>
<p>Программа использует connection pool по шаблону:</p>
<p>Инициализация:</p>
<figure class='code'> <div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
</pre></td><td class='code'><pre><code class='java'><span class='line'> <span class="n">ConnectionPool</span> <span class="n">pool</span> <span class="o">=</span> <span class="n">ConnectionPool</span><span class="o">.</span><span class="na">getInstance</span><span class="o">();</span>
</span><span class='line'> <span class="n">pool</span><span class="o">.</span><span class="na">setUsername</span><span class="o">(</span><span class="s">"user1"</span><span class="o">);<</span><span class="n">br</span> <span class="o">/></span> <span class="n">pool</span><span class="o">.</span><span class="na">setPassword</span><span class="o">(</span><span class="s">"bebebe"</span><span class="o">);</span>
</span><span class='line'> <span class="n">pool</span><span class="o">.</span><span class="na">setPath</span><span class="o">(</span><span class="s">"jdbc:postgresql://hostname/main"</span><span class="o">);</span>
</span><span class='line'> <span class="n">pool</span><span class="o">.</span><span class="na">setClassName</span><span class="o">(</span><span class="s">"org.postgresql.Driver"</span><span class="o">);</span>
</span><span class='line'> <span class="n">pool</span><span class="o">.</span><span class="na">setPoolsize</span><span class="o">(</span><span class="mi">5</span><span class="o">);</span> <span class="c1">// держать 5 коннекций </span>
</span><span class='line'> <span class="k">if</span> <span class="o">(!</span> <span class="n">pool</span><span class="o">.</span><span class="na">init</span><span class="o">()</span> <span class="o">)</span> <span class="n">System</span><span class="o">.</span><span class="na">exit</span><span class="o">(</span><span class="mi">100</span><span class="o">);</span>
</span></code></pre></td></tr></table></div></figure>
<p>Тут все просто, берем экземпляр connectionpool-а (проект небольшой,
так что оформим его в виде <em>singleton</em>, устанавливаем параметры, и
если не удалось инициализировать, то не судьба и программу
выполнять…</p>
<p>И дальше, в том месте где используется соединение, что-то вроде:</p>
<figure class='code'> <div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
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</pre></td><td class='code'><pre><code class='java'><span class='line'> <span class="n">Connection</span> <span class="n">dbconnection</span> <span class="o">=</span> <span class="n">ConnectionPool</span><span class="o">.</span><span class="na">getConnection</span><span class="o">();</span>
</span><span class='line'> <span class="k">try</span> <span class="o">{</span>
</span><span class='line'> <span class="o">....</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'><span class="n">finaly</span>
</span><span class='line'> <span class="o">{</span>
</span><span class='line'> <span class="n">ConnectionPool</span><span class="o">.</span><span class="na">releaseConnection</span><span class="o">(</span><span class="n">dbconnection</span><span class="o">);</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span></code></pre></td></tr></table></div></figure>
<p> Тут, если посмотреть, то connection берется не из экземпляра
connection pool, а из статического метода в классе. И таким же образом
отдается. Если у нас connection pool в виде singleton – зачем
переливать из пустого в порожнее, брать по очереди connection pool и
затем из него connection? Взять экземпляр connection pool я могу и сам
в статическом методе. Мелочь, но писать программы проще…</p>
<h2>Как это все реализoвано.</h2>
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</pre></td><td class='code'><pre><code class='java'><span class='line'><span class="kn">import</span> <span class="nn">java.sql.Connection</span><span class="o">;</span>
</span><span class='line'><span class="kn">import</span> <span class="nn">java.util.Queue</span><span class="o">;</span>
</span><span class='line'><span class="kn">import</span> <span class="nn">java.util.concurrent.ConcurrentLinkedQueue</span><span class="o">;</span>
</span><span class='line'><span class="kn">import</span> <span class="nn">java.util.logging.Logger</span><span class="o">;</span>
</span><span class='line'>
</span><span class='line'><span class="kd">public</span> <span class="kd">class</span> <span class="nc">ConnectionPool</span> <span class="o">{</span>
</span><span class='line'> <span class="kd">private</span> <span class="kd">static</span> <span class="n">ConnectionPool</span> <span class="n">instance</span><span class="o">;</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">private</span> <span class="nf">ConnectionPool</span><span class="o">()</span> <span class="o">{</span>
</span><span class='line'> <span class="n">connections</span> <span class="o">=</span> <span class="k">new</span> <span class="n">ConcurrentLinkedQueue</span><span class="o"><</span><span class="n">connection</span><span class="o">>();</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="kd">static</span> <span class="n">ConnectionPool</span> <span class="nf">getInstance</span><span class="o">()</span> <span class="o">{</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(</span><span class="n">instance</span> <span class="o">==</span> <span class="kc">null</span><span class="o">)</span> <span class="n">instance</span> <span class="o">=</span> <span class="k">new</span> <span class="n">ConnectionPool</span><span class="o">();</span>
</span><span class='line'> <span class="k">return</span> <span class="n">instance</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="kd">static</span> <span class="n">Connection</span> <span class="nf">getConnection</span><span class="o">()</span> <span class="o">{</span>
</span><span class='line'> <span class="k">return</span> <span class="nf">getInstance</span><span class="o">().</span><span class="na">getInstanceConnection</span><span class="o">();</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="kd">static</span> <span class="kt">void</span> <span class="nf">releaseConnection</span><span class="o">(</span><span class="n">Connection</span> <span class="n">c</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="n">getInstance</span><span class="o">().</span><span class="na">releaseInstanceConnection</span><span class="o">(</span><span class="n">c</span><span class="o">);</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'><span class="cm">/**</span>
</span><span class='line'><span class="cm"> * Выделить соединение из пула.</span>
</span><span class='line'><span class="cm"> * логика такая:</span>
</span><span class='line'><span class="cm"> * если не пустой - взять соединение из пула, проверить на валидность</span>
</span><span class='line'><span class="cm"> * и вернуть. невалидные соединения сразу убиваем.</span>
</span><span class='line'><span class="cm"> * если пул пустой - сделать новое соединение и вернуть его. Если не смогли</span>
</span><span class='line'><span class="cm"> * сделать новое соединение (типа DB сервер умер) - просто жалуемся в лог </span>
</span><span class='line'><span class="cm"> * и возвращаем null</span>
</span><span class='line'><span class="cm"> */</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">private</span> <span class="n">Connection</span> <span class="nf">getInstanceConnection</span><span class="o">()</span> <span class="o">{</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(!</span> <span class="n">alreadyInitialized</span><span class="o">){</span>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">severe</span><span class="o">(</span><span class="s">"improper using of db pool (getConnection without init)"</span><span class="o">);</span>
</span><span class='line'> <span class="k">return</span> <span class="kc">null</span><span class="o">;</span>
</span><span class='line'> <span class="o">};</span>
</span><span class='line'> <span class="n">Connection</span> <span class="n">currentConnection</span><span class="o">;</span>
</span><span class='line'> <span class="k">do</span> <span class="o">{</span>
</span><span class='line'> <span class="n">currentConnection</span> <span class="o">=</span> <span class="n">connections</span><span class="o">.</span><span class="na">poll</span><span class="o">();</span>
</span><span class='line'>
</span><span class='line'> <span class="k">if</span> <span class="o">(</span><span class="n">currentConnection</span> <span class="o">==</span> <span class="kc">null</span><span class="o">)</span> <span class="k">break</span><span class="o">;</span> <span class="c1">//пустой пул</span>
</span><span class='line'> <span class="c1">// если дохлое соединение - не будем его использовать</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(!</span> <span class="n">validConnection</span><span class="o">(</span><span class="n">currentConnection</span><span class="o">))</span> <span class="o">{</span>
</span><span class='line'> <span class="n">currentConnection</span> <span class="o">=</span> <span class="kc">null</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'> <span class="o">}</span> <span class="k">while</span> <span class="o">(</span><span class="n">currentConnection</span> <span class="o">==</span> <span class="kc">null</span><span class="o">);</span>
</span><span class='line'>
</span><span class='line'> <span class="k">try</span><span class="o">{</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(</span><span class="n">connections</span><span class="o">.</span><span class="na">size</span><span class="o">()</span> <span class="o">==</span> <span class="mi">0</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">info</span><span class="o">(</span><span class="s">"DB Pool depleted, add new connection"</span><span class="o">);</span>
</span><span class='line'> <span class="n">connections</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="n">java</span><span class="o">.</span><span class="na">sql</span><span class="o">.</span><span class="na">DriverManager</span><span class="o">.</span><span class="na">getConnection</span><span class="o">(</span><span class="n">path</span><span class="o">,</span> <span class="n">userName</span><span class="o">,</span><span class="n">password</span><span class="o">));</span>
</span><span class='line'> <span class="n">currentConnection</span> <span class="o">=</span> <span class="n">connections</span><span class="o">.</span><span class="na">poll</span><span class="o">();</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(!</span> <span class="n">validConnection</span><span class="o">(</span><span class="n">currentConnection</span><span class="o">))</span> <span class="o">{</span>
</span><span class='line'> <span class="c1">// не судьба. Сдаемся</span>
</span><span class='line'> <span class="k">throw</span> <span class="k">new</span> <span class="nf">Exception</span><span class="o">(</span><span class="s">"new connection also is not valid"</span><span class="o">);</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'> <span class="o">}</span> <span class="k">catch</span> <span class="o">(</span><span class="n">Exception</span> <span class="n">ie</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">severe</span><span class="o">(</span><span class="s">"cannot provide sql connection:"</span><span class="o">+</span><span class="n">ie</span><span class="o">);</span>
</span><span class='line'> <span class="k">return</span> <span class="kc">null</span><span class="o">;</span>
</span><span class='line'> <span class="o">};</span>
</span><span class='line'> <span class="k">return</span> <span class="n">currentConnection</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">private</span> <span class="kt">void</span> <span class="nf">releaseInstanceConnection</span><span class="o">(</span><span class="n">Connection</span> <span class="n">c</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(!</span> <span class="n">alreadyInitialized</span><span class="o">){</span>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">severe</span><span class="o">(</span><span class="s">"improper using of db pool (releseConnection without init)"</span><span class="o">);</span>
</span><span class='line'> <span class="k">return</span><span class="o">;</span>
</span><span class='line'> <span class="o">};</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(</span><span class="n">getCurrentSize</span><span class="o">()</span> <span class="o">>=</span> <span class="n">getMaxPoolSize</span><span class="o">())</span> <span class="o">{</span>
</span><span class='line'> <span class="k">try</span> <span class="o">{</span> <span class="n">c</span><span class="o">.</span><span class="na">close</span><span class="o">();</span> <span class="o">}</span> <span class="k">catch</span> <span class="o">(</span><span class="n">Exception</span> <span class="n">e</span><span class="o">)</span> <span class="o">{};</span>
</span><span class='line'> <span class="o">}</span> <span class="k">else</span> <span class="k">if</span> <span class="o">(!</span> <span class="n">validConnection</span><span class="o">(</span><span class="n">c</span><span class="o">)</span> <span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="c1">// Не будем возвращать в пул дохлое соединение</span>
</span><span class='line'> <span class="o">}</span> <span class="k">else</span> <span class="o">{</span>
</span><span class='line'> <span class="n">connections</span><span class="o">.</span><span class="na">offer</span><span class="o">(</span><span class="n">c</span><span class="o">);</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'>
</span><span class='line'> <span class="kd">private</span> <span class="kt">int</span> <span class="n">maxPoolSize</span> <span class="o">=</span> <span class="mi">5</span><span class="o">;</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="kt">int</span>
</span><span class='line'> <span class="nf">getMaxPoolSize</span><span class="o">()</span> <span class="o">{</span>
</span><span class='line'> <span class="k">return</span> <span class="n">maxPoolSize</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">setPoolsize</span><span class="o">(</span><span class="kt">int</span> <span class="n">maxPoolSize</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(!</span><span class="n">alreadyInitialized</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">this</span><span class="o">.</span><span class="na">maxPoolSize</span> <span class="o">=</span> <span class="n">maxPoolSize</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span> <span class="k">else</span> <span class="o">{</span>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">severe</span><span class="o">(</span><span class="s">"setPoolsize after init. ignoring"</span><span class="o">);</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="kt">int</span> <span class="nf">getCurrentSize</span><span class="o">()</span> <span class="o">{</span>
</span><span class='line'> <span class="k">return</span> <span class="n">connections</span><span class="o">.</span><span class="na">size</span><span class="o">();</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">private</span> <span class="n">String</span> <span class="n">userName</span><span class="o">;</span>
</span><span class='line'> <span class="kd">private</span> <span class="n">String</span> <span class="n">password</span><span class="o">;</span>
</span><span class='line'> <span class="kd">private</span> <span class="n">String</span> <span class="n">path</span><span class="o">;</span>
</span><span class='line'> <span class="kd">private</span> <span class="n">String</span> <span class="n">className</span><span class="o">;</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="n">String</span> <span class="nf">getUserName</span><span class="o">()</span> <span class="o">{</span>
</span><span class='line'> <span class="k">return</span> <span class="n">userName</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">setUsername</span><span class="o">(</span><span class="n">String</span> <span class="n">userName</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(!</span><span class="n">alreadyInitialized</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">this</span><span class="o">.</span><span class="na">userName</span> <span class="o">=</span> <span class="n">userName</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span> <span class="k">else</span> <span class="o">{</span>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">severe</span><span class="o">(</span><span class="s">"setUserName after init. ignoring"</span><span class="o">);</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="n">String</span> <span class="nf">getPassword</span><span class="o">()</span> <span class="o">{</span>
</span><span class='line'> <span class="k">return</span> <span class="n">password</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">setPassword</span><span class="o">(</span><span class="n">String</span> <span class="n">password</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(!</span><span class="n">alreadyInitialized</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">this</span><span class="o">.</span><span class="na">password</span> <span class="o">=</span> <span class="n">password</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span> <span class="k">else</span> <span class="o">{</span>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">severe</span><span class="o">(</span><span class="s">"setPassword after init. ignoring"</span><span class="o">);</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="n">String</span> <span class="nf">getPath</span><span class="o">()</span> <span class="o">{</span>
</span><span class='line'> <span class="k">return</span> <span class="n">path</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">setPath</span><span class="o">(</span><span class="n">String</span> <span class="n">path</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(!</span><span class="n">alreadyInitialized</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">this</span><span class="o">.</span><span class="na">path</span> <span class="o">=</span> <span class="n">path</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span> <span class="k">else</span> <span class="o">{</span>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">severe</span><span class="o">(</span><span class="s">"Path after init. ignoring"</span><span class="o">);</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="n">String</span> <span class="nf">getClassName</span><span class="o">()</span> <span class="o">{</span>
</span><span class='line'> <span class="k">return</span> <span class="n">className</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">setClassName</span><span class="o">(</span><span class="n">String</span> <span class="n">className</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(!</span><span class="n">alreadyInitialized</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">this</span><span class="o">.</span><span class="na">className</span> <span class="o">=</span> <span class="n">className</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span> <span class="k">else</span> <span class="o">{</span>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">severe</span><span class="o">(</span><span class="s">"setClassName after init. ignoring"</span><span class="o">);</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="cm">/**</span>
</span><span class='line'><span class="cm"> * init - Инициализация пула сообщений</span>
</span><span class='line'><span class="cm"> * @return boolean - успешно ли инициализирован пул (true - все хорошо)</span>
</span><span class='line'><span class="cm"> */</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">public</span> <span class="kd">synchronized</span> <span class="kt">boolean</span> <span class="nf">init</span><span class="o">()</span> <span class="o">{</span>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">entering</span><span class="o">(</span><span class="s">"ConnectionPool"</span><span class="o">,</span><span class="s">"init"</span><span class="o">);</span>
</span><span class='line'> <span class="k">try</span> <span class="o">{</span>
</span><span class='line'> <span class="k">if</span> <span class="o">(</span><span class="n">alreadyInitialized</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">throw</span> <span class="k">new</span> <span class="nf">Exception</span><span class="o">(</span><span class="s">"Double init of db pool"</span><span class="o">);</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="n">Class</span><span class="o">.</span><span class="na">forName</span><span class="o">(</span><span class="k">this</span><span class="o">.</span><span class="na">className</span><span class="o">);</span>
</span><span class='line'> <span class="k">for</span> <span class="o">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">1</span><span class="o">;</span> <span class="n">i</span><span class="o"><=</span><span class="mi">5</span><span class="o">;</span> <span class="n">i</span><span class="o">++){</span>
</span><span class='line'> <span class="n">connections</span><span class="o">.</span><span class="na">add</span><span class="o">(</span><span class="n">java</span><span class="o">.</span><span class="na">sql</span><span class="o">.</span><span class="na">DriverManager</span>
</span><span class='line'> <span class="o">.</span><span class="na">getConnection</span><span class="o">(</span><span class="n">path</span><span class="o">,</span> <span class="n">userName</span><span class="o">,</span><span class="n">password</span><span class="o">));</span>
</span><span class='line'> <span class="o">};</span>
</span><span class='line'> <span class="n">alreadyInitialized</span> <span class="o">=</span> <span class="kc">true</span><span class="o">;</span>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">exiting</span><span class="o">(</span><span class="s">"ConnectionPool"</span><span class="o">,</span><span class="s">"init"</span><span class="o">);</span>
</span><span class='line'> <span class="k">return</span> <span class="kc">true</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span> <span class="k">catch</span> <span class="o">(</span><span class="n">Exception</span> <span class="n">e</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">severe</span><span class="o">(</span><span class="s">"Cannot init db pool:"</span><span class="o">+</span><span class="n">e</span><span class="o">);</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">exiting</span><span class="o">(</span><span class="s">"ConnectionPool"</span><span class="o">,</span><span class="s">"init"</span><span class="o">);</span>
</span><span class='line'> <span class="k">return</span> <span class="kc">false</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">private</span> <span class="kd">static</span> <span class="n">Logger</span> <span class="n">log</span> <span class="o">=</span> <span class="n">Logger</span><span class="o">.</span><span class="na">getLogger</span><span class="o">(</span><span class="s">"dbpool"</span><span class="o">);</span>
</span><span class='line'>
</span><span class='line'> <span class="cm">/**</span>
</span><span class='line'><span class="cm"> * Хранилище для коннекций</span>
</span><span class='line'><span class="cm"> */</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">private</span> <span class="n">ConcurrentLinkedQueue</span><span class="o"><</span><span class="n">connection</span><span class="o">></span> <span class="n">connections</span><span class="o">;</span>
</span><span class='line'>
</span><span class='line'>
</span><span class='line'> <span class="cm">/**</span>
</span><span class='line'><span class="cm"> * переменная предотвращающая двойную инициализацию DB pool</span>
</span><span class='line'><span class="cm"> */</span>
</span><span class='line'> <span class="kd">private</span> <span class="kt">boolean</span> <span class="n">alreadyInitialized</span> <span class="o">=</span> <span class="kc">false</span><span class="o">;</span>
</span><span class='line'> <span class="cm">/**</span>
</span><span class='line'><span class="cm"> * Проверка что соединение до сих пор живо. Если есть проблемы, мы его</span>
</span><span class='line'><span class="cm"> * просто убьем</span>
</span><span class='line'><span class="cm"> *</span>
</span><span class='line'><span class="cm"> * Проверяем просто делая setAutoCommit. Если никаких exceptions</span>
</span><span class='line'><span class="cm"> * не последовало, считаем что все в порядке.</span>
</span><span class='line'><span class="cm"> */</span>
</span><span class='line'>
</span><span class='line'> <span class="kd">private</span> <span class="kt">boolean</span> <span class="nf">validConnection</span><span class="o">(</span><span class="n">java</span><span class="o">.</span><span class="na">sql</span><span class="o">.</span><span class="na">Connection</span> <span class="n">c</span><span class="o">)</span> <span class="o">{</span>
</span><span class='line'> <span class="k">try</span> <span class="o">{</span>
</span><span class='line'> <span class="kt">boolean</span> <span class="n">status</span> <span class="o">=</span> <span class="n">c</span><span class="o">.</span><span class="na">getAutoCommit</span><span class="o">();</span>
</span><span class='line'> <span class="n">c</span><span class="o">.</span><span class="na">setAutoCommit</span><span class="o">(!</span> <span class="n">status</span><span class="o">);</span>
</span><span class='line'> <span class="n">c</span><span class="o">.</span><span class="na">setAutoCommit</span><span class="o">(</span><span class="n">status</span><span class="o">);</span>
</span><span class='line'> <span class="o">}</span> <span class="k">catch</span> <span class="o">(</span><span class="n">Exception</span> <span class="n">e</span><span class="o">)</span>
</span><span class='line'> <span class="o">{</span>
</span><span class='line'> <span class="k">try</span> <span class="o">{</span> <span class="n">c</span><span class="o">.</span><span class="na">close</span><span class="o">();</span> <span class="o">}</span> <span class="k">catch</span> <span class="o">(</span><span class="n">Exception</span> <span class="n">notImportant</span><span class="o">)</span> <span class="o">{};</span>
</span><span class='line'> <span class="n">log</span><span class="o">.</span><span class="na">info</span><span class="o">(</span><span class="s">"Dead sql connection detected"</span><span class="o">);</span>
</span><span class='line'> <span class="k">return</span> <span class="kc">false</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'> <span class="k">return</span> <span class="kc">true</span><span class="o">;</span>
</span><span class='line'> <span class="o">}</span>
</span><span class='line'><span class="o">}</span>
</span></code></pre></td></tr></table></div></figure>
<p></p>