Strange error when saving the tiddlywiki

[CGenie]

I can reproduce this on my android phone and on Chrome: when saving, I get "Error while saving: XMLHttpRequest error code: 423".
It seems however that the file is saved correctly.

[OutOfBrain]

Had the same happening to me. The file was corrupted afterwards though. Happened after (seemingly) too frequent saves (multiple within a couple of seconds).
Maybe a race condition on safe?

[qbit]

Looks like TW is trying to modify the served wiki while another http request is happening (maybe a background save?).

@OutOfBrain are you also on android?

[AlexRamallo]

This happened to me today on iOS, and resulted in a corrupted wiki so it's just a blank page when you open it.

[qbit]

I haven't been able to repro this. Can anyone offer more details on their usage? Perhaps install with -race enabled?

Do you have the wiki file open in multiple tabs?

[AlexRamallo]

I can reproduce it on my server. The error occurs when you have multiple overlapping PUT requests.

In my case, I'm running widdler I'm hosting a ~20mb wiki behind a reverse proxy. Save requests are pretty slow, so it's easy to accidentally send multiple.

[AlexRamallo]

Update and clarification: the overlapping saves are what cause the error message, but I haven't been able to get it to reliable corrupt the wiki with that alone.

However, if I start a save request on my phone, and then immediately close the browser or change tabs before the save completes, then it will corrupt 100% of the time. I'm guessing iOS interrupts xhr requests when a tab is in the background or something?

[qbit]

Ok, I think I have a solution for the 423 issue but I think the corruption when saving is interrupted will be more involved.

[qbit]

Would anyone hitting the 423 issue be willing to try the muxd-handlers branch?

[CGenie]

I'm not a go expert. I installed it with snap on Ubuntu (v. 1.17) and ran:

 go install suah.dev/widdler@muxd-handlers

but got this error:

go: downloading suah.dev/widdler v1.1.4-0.20211209124834-f9de42e80131
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/internal/xml/marshal.go:8:2: package bufio is not in GOROOT (/usr/lib/go/src/bufio)
../../../go/pkg/mod/golang.org/x/[email protected]/terminal.go:8:2: package bytes is not in GOROOT (/usr/lib/go/src/bytes)
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/lock.go:8:2: package container/heap is not in GOROOT (/usr/lib/go/src/container/heap)
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/file.go:8:2: package context is not in GOROOT (/usr/lib/go/src/context)
../../../go/pkg/mod/golang.org/x/[email protected]/bcrypt/bcrypt.go:11:2: package crypto/rand is not in GOROOT (/usr/lib/go/src/crypto/rand)
../../../go/pkg/mod/golang.org/x/[email protected]/bcrypt/bcrypt.go:12:2: package crypto/subtle is not in GOROOT (/usr/lib/go/src/crypto/subtle)
../../../go/pkg/mod/suah.dev/[email protected]/main.go:4:2: package crypto/tls is not in GOROOT (/usr/lib/go/src/crypto/tls)
../../../go/pkg/mod/suah.dev/[email protected]/main.go:5:2: package embed is not in GOROOT (/usr/lib/go/src/embed)
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/internal/xml/marshal.go:10:2: package encoding is not in GOROOT (/usr/lib/go/src/encoding)
../../../go/pkg/mod/golang.org/x/[email protected]/bcrypt/base64.go:7:8: package encoding/base64 is not in GOROOT (/usr/lib/go/src/encoding/base64)
../../../go/pkg/mod/golang.org/x/[email protected]/unix/syscall_linux.go:15:2: package encoding/binary is not in GOROOT (/usr/lib/go/src/encoding/binary)
../../../go/pkg/mod/suah.dev/[email protected]/main.go:6:2: package encoding/csv is not in GOROOT (/usr/lib/go/src/encoding/csv)
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/file.go:9:2: package encoding/xml is not in GOROOT (/usr/lib/go/src/encoding/xml)
../../../go/pkg/mod/golang.org/x/[email protected]/bcrypt/bcrypt.go:13:2: package errors is not in GOROOT (/usr/lib/go/src/errors)
../../../go/pkg/mod/suah.dev/[email protected]/main.go:7:2: package flag is not in GOROOT (/usr/lib/go/src/flag)
../../../go/pkg/mod/suah.dev/[email protected]/main.go:8:2: package fmt is not in GOROOT (/usr/lib/go/src/fmt)
../../../go/pkg/mod/golang.org/x/[email protected]/bcrypt/bcrypt.go:15:2: package io is not in GOROOT (/usr/lib/go/src/io)
../../../go/pkg/mod/suah.dev/[email protected]/main.go:9:2: package io/ioutil is not in GOROOT (/usr/lib/go/src/io/ioutil)
../../../go/pkg/mod/suah.dev/[email protected]/main.go:10:2: package log is not in GOROOT (/usr/lib/go/src/log)
../../../go/pkg/mod/golang.org/x/[email protected]/unix/affinity_linux.go:10:2: package math/bits is not in GOROOT (/usr/lib/go/src/math/bits)
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/prop.go:14:2: package mime is not in GOROOT (/usr/lib/go/src/mime)
../../../go/pkg/mod/suah.dev/[email protected]/main.go:11:2: package net is not in GOROOT (/usr/lib/go/src/net)
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/file.go:11:2: package net/http is not in GOROOT (/usr/lib/go/src/net/http)
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/webdav.go:13:2: package net/url is not in GOROOT (/usr/lib/go/src/net/url)
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/file.go:12:2: package os is not in GOROOT (/usr/lib/go/src/os)
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/file.go:13:2: package path is not in GOROOT (/usr/lib/go/src/path)
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/file.go:14:2: package path/filepath is not in GOROOT (/usr/lib/go/src/path/filepath)
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/internal/xml/marshal.go:13:2: package reflect is not in GOROOT (/usr/lib/go/src/reflect)
../../../go/pkg/mod/suah.dev/[email protected]/main.go:16:2: package regexp is not in GOROOT (/usr/lib/go/src/regexp)
../../../go/pkg/mod/golang.org/x/[email protected]/unix/ioctl.go:11:2: package runtime is not in GOROOT (/usr/lib/go/src/runtime)
../../../go/pkg/mod/golang.org/x/[email protected]/unix/syscall_unix.go:12:2: package sort is not in GOROOT (/usr/lib/go/src/sort)
../../../go/pkg/mod/golang.org/x/[email protected]/blowfish/cipher.go:19:8: package strconv is not in GOROOT (/usr/lib/go/src/strconv)
../../../go/pkg/mod/golang.org/x/[email protected]/unix/syscall.go:30:2: package strings is not in GOROOT (/usr/lib/go/src/strings)
../../../go/pkg/mod/golang.org/x/[email protected]/unix/syscall_unix.go:13:2: package sync is not in GOROOT (/usr/lib/go/src/sync)
../../../go/pkg/mod/golang.org/x/[email protected]/unix/aliases.go:11:8: package syscall is not in GOROOT (/usr/lib/go/src/syscall)
../../../go/pkg/mod/suah.dev/[email protected]/main.go:19:2: package text/template is not in GOROOT (/usr/lib/go/src/text/template)
../../../go/pkg/mod/golang.org/x/[email protected]/unix/timestruct.go:10:8: package time is not in GOROOT (/usr/lib/go/src/time)
../../../go/pkg/mod/golang.org/x/[email protected]/webdav/internal/xml/xml.go:24:2: package unicode is not in GOROOT (/usr/lib/go/src/unicode)
../../../go/pkg/mod/golang.org/x/[email protected]/terminal.go:13:2: package unicode/utf8 is not in GOROOT (/usr/lib/go/src/unicode/utf8)
../../../go/pkg/mod/golang.org/x/[email protected]/internal/unsafeheader/unsafeheader.go:14:2: package unsafe is not in GOROOT (/usr/lib/go/src/unsafe)

[CGenie]

Ah OK export GOROOT=/snap/go/8779 fixed this.

[CGenie]

I still experience that error. Not on localhost, but I host widdler on a rock64 (arm) machine, maybe it's because of it's slowness that saving takes so long. I reproduce the error when making changes, then the red "save" button shows up (it's autosaving in the background I guess but it takes time), then I click that red "save" checkbox again and error shows up (on muxd-handlers as well).

[qbit]

Ok, dang. I have been testing on localhost (loading a wiki up with a large number of images) - I'll try a remote install to see if I can repro

[CGenie]

Maybe you can add sleep to the PUT handler. :)

[qbit]

Alright, anyone wanna try 1.2.0? (go install suah.dev/widdler@latest)

I extended the locking a bit (shout out to diamondburned in #go-lang:matrix.org for the pointers!).

I still haven't been able to repro the 423 error. My vps is running OpenBSD.. maybe that has something to do with it - I will continue testing with a linux box and see what I get.

[AlexRamallo]

I just tested it and it seems like the error from overlapping requests is gone (the corruption issue still exists though)

To test locally, I used Firefox's network throttling feature (under the network tab in the dev tools). I sent overlapping save requests this way and didn't encounter the error from before. I also repeated it with version 1.1.3 to verify, and I did get the error in the older version.

On the 1.1.3 test I didn't get error 423 either, just an ajax error with error code 0. I wasn't able to reproduce the 423 error either.

[qbit]

@AlexRamallo thanks for including the testing steps! I'll think more on the corruption.