From 57c3848c8f588dfa8524f18b1225dc65b3794cc3 Mon Sep 17 00:00:00 2001
From: Pawel Filipczak <pawel.filipczak@elastic.co>
Date: Tue, 10 Sep 2024 15:24:02 +0200
Subject: [PATCH] Class interface instrumentation (#87)

---
 .../code/InternalFunctionInstrumentation.cpp  | 33 +++++++++++++--
 .../phpt/tests/instrumentation_interface.phpt | 42 +++++++++++++++++++
 prod/native/libcommon/code/LoggerInterface.h  |  2 +-
 3 files changed, 73 insertions(+), 4 deletions(-)
 create mode 100644 prod/native/extension/phpt/tests/instrumentation_interface.phpt

diff --git a/prod/native/extension/code/InternalFunctionInstrumentation.cpp b/prod/native/extension/code/InternalFunctionInstrumentation.cpp
index b1cfbe3..34d1786 100644
--- a/prod/native/extension/code/InternalFunctionInstrumentation.cpp
+++ b/prod/native/extension/code/InternalFunctionInstrumentation.cpp
@@ -352,7 +352,7 @@ bool instrumentFunction(LoggerInterface *log, std::string_view cName, std::strin
     zend_ulong funcHash = ZSTR_HASH(func->common.function_name);
     zend_ulong hash = classHash ^ (funcHash << 1);
 
-    ELOG_DEBUG(log, "instrumentFunction 0x%X " PRsv "::" PRsv " type: %s is instrumented", hash, PRsvArg(className), PRsvArg(functionName), func->common.type == ZEND_INTERNAL_FUNCTION ? "internal" : "user");
+    ELOG_DEBUG(log, "instrumentFunction 0x%X " PRsv "::" PRsv " type: %s is marked to be instrumented", hash, PRsvArg(className), PRsvArg(functionName), func->common.type == ZEND_INTERNAL_FUNCTION ? "internal" : "user");
 
     reinterpret_cast<InstrumentedFunctionHooksStorage_t *>(EAPM_GL(hooksStorage_).get())->store(hash, AutoZval{callableOnEntry}, AutoZval{callableOnExit});
 
@@ -432,11 +432,38 @@ zend_observer_fcall_handlers elasticRegisterObserver(zend_execute_data *execute_
     if (!callbacks) {
         if (EAPM_GL(logger_)->doesMeetsLevelCondition(LogLevel::logLevel_trace)) {
             auto [cls, func] = getClassAndFunctionName(execute_data);
-            ELOG_TRACE(EAPM_GL(logger_), "elasticRegisterObserver hash: 0x%X " PRsv "::" PRsv ", not instrumented", hash, PRsvArg(cls), PRsvArg(func));
+            ELOG_TRACE(EAPM_GL(logger_), "elasticRegisterObserver hash: 0x%X " PRsv "::" PRsv ", not marked to be instrumented", hash, PRsvArg(cls), PRsvArg(func));
         }
+
+        auto ce = execute_data->func->common.scope;
+        if (!ce) {
+            return {nullptr, nullptr};
+        }
+
+        // lookup for class interfaces
+        for (uint32_t i = 0; i < ce->num_interfaces; ++i) {
+            auto classHash = ZSTR_HASH(ce->interfaces[i]->name);
+            zend_ulong funcHash = ZSTR_HASH(execute_data->func->common.function_name);
+            zend_ulong ifaceHash = classHash ^ (funcHash << 1);
+
+            callbacks = reinterpret_cast<InstrumentedFunctionHooksStorage_t *>(EAPM_GL(hooksStorage_).get())->find(ifaceHash);
+            if (callbacks) {
+                if (EAPM_GL(logger_)->doesMeetsLevelCondition(LogLevel::logLevel_trace)) {
+                    auto [cls, func] = getClassAndFunctionName(execute_data);
+                    ELOG_TRACE(EAPM_GL(logger_), "elasticRegisterObserver hash: 0x%X " PRsv "::" PRsv ", will be instrumented because interface 0x%X '" PRsv "' was marked to be instrumented", hash, PRsvArg(cls), PRsvArg(func), ifaceHash, PRzsArg(ce->interfaces[i]->name));
+                }
+                // copy callbacks from interface storage hash to implementation hash
+                for (auto &item : *callbacks) {
+                    reinterpret_cast<InstrumentedFunctionHooksStorage_t *>(EAPM_GL(hooksStorage_).get())->store(hash, AutoZval(item.first.get()), AutoZval(item.second.get()));
+                }
+                break;
+            }
+        }
+    }
+
+    if (!callbacks) {
         return {nullptr, nullptr};
     }
-    ELOG_TRACE(EAPM_GL(logger_), "elasticRegisterObserver hash: 0x%X", hash);
 
     bool havePreHook = false;
     bool havePostHook = false;
diff --git a/prod/native/extension/phpt/tests/instrumentation_interface.phpt b/prod/native/extension/phpt/tests/instrumentation_interface.phpt
new file mode 100644
index 0000000..a1aa46c
--- /dev/null
+++ b/prod/native/extension/phpt/tests/instrumentation_interface.phpt
@@ -0,0 +1,42 @@
+--TEST--
+instrumentation - interface
+--ENV--
+ELASTIC_OTEL_LOG_LEVEL_STDERR=info
+--INI--
+extension=/elastic/elastic_otel_php.so
+elastic_otel.bootstrap_php_part_file={PWD}/includes/bootstrap_mock.inc
+--FILE--
+<?php
+declare(strict_types=1);
+
+interface ImplementationInterface
+{
+    public function testfunc();
+}
+
+class Implementation implements ImplementationInterface
+{
+    public function testfunc()
+    {
+        echo "TestFunc".PHP_EOL;
+    }
+}
+
+
+elastic_otel_hook("ImplementationInterface", "testfunc", function () {
+	echo "*** prehook() called from impl\n";
+ }, function () {
+	echo "*** posthook() called from impl\n";
+});
+
+$impl = new Implementation;
+
+$impl->testfunc();
+
+echo "Test completed\n";
+?>
+--EXPECTF--
+*** prehook() called from impl
+TestFunc
+*** posthook() called from impl
+Test completed
diff --git a/prod/native/libcommon/code/LoggerInterface.h b/prod/native/libcommon/code/LoggerInterface.h
index e033986..e83f424 100644
--- a/prod/native/libcommon/code/LoggerInterface.h
+++ b/prod/native/libcommon/code/LoggerInterface.h
@@ -38,7 +38,7 @@ class LoggerInterface {
 #define PRsv "%.*s"
 #define PRsvArg(strv) static_cast<int>(strv.length()), strv.data()
 #define PRcsvArg(str, len) len, str
-
+#define PRzsArg(strv) ZSTR_LEN(strv), ZSTR_VAL(strv)
 
 #define ELOG_CRITICAL(logger, format, ...) do { if (!logger || !logger->doesMeetsLevelCondition(LogLevel::logLevel_critical)) break; logger->printf(LogLevel::logLevel_critical, format, ##__VA_ARGS__); } while(false);
 #define ELOG_ERROR(logger, format, ...) do { if (!logger || !logger->doesMeetsLevelCondition(LogLevel::logLevel_error)) break; logger->printf(LogLevel::logLevel_error, format, ##__VA_ARGS__); } while(false);