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Fix multiple bugs in ThreadedFileEventDriver.

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- Errors were reported as "ok"
- The cancel state logic was flawed and could lose cancel requests
- Operations could be removed from the active sets before they actually finished, causing the callback to never get called
This commit is contained in:
Sönke Ludwig 2017-08-14 01:58:42 +02:00
parent dd873ec6cf
commit a63907b9f7
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GPG key ID: D95E8DB493EE314C
1 changed files with 34 additions and 37 deletions
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71
source/eventcore/drivers/threadedfile.d
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@ -61,11 +61,12 @@ final class ThreadedFileEventDriver(Events : EventDriverEvents) : EventDriverFil
private {
enum ThreadedFileStatus {
idle, // -> processing
processing, // -> cancelling, finished
cancelling, // -> cancelled
cancelled, // -> idle
finished // -> idle
idle, // -> initiated (by caller)
initiated, // -> processing (by worker)
processing, // -> cancelling, finished (by caller, worker)
cancelling, // -> cancelled (by worker)
cancelled, // -> idle (by event receiver)
finished // -> idle (by event receiver)
}
static struct IOInfo {
@ -74,14 +75,18 @@ final class ThreadedFileEventDriver(Events : EventDriverEvents) : EventDriverFil
shared size_t bytesWritten;
IOStatus ioStatus;
void flush(FileFD fd)
void finalize(FileFD fd, scope void delegate() @safe nothrow pre_cb)
@safe nothrow {
if (() @trusted { return cas(&this.status, ThreadedFileStatus.finished, ThreadedFileStatus.idle); } ()) {
pre_cb();
auto cb = this.callback;
this.callback = null;
log("fire callback");
cb(fd, IOStatus.ok, safeAtomicLoad(this.bytesWritten));
if (cb) {
log("fire callback");
cb(fd, ioStatus, safeAtomicLoad(this.bytesWritten));
}
} else if (() @trusted { return cas(&this.status, ThreadedFileStatus.cancelled, ThreadedFileStatus.idle); } ()) {
pre_cb();
this.callback = null;
log("ignore callback due to cancellation");
}
@ -153,7 +158,7 @@ final class ThreadedFileEventDriver(Events : EventDriverEvents) : EventDriverFil
auto flags = () @trusted { return fcntl(system_file_handle, F_GETFD); } ();
if (flags == -1) return FileFD.invalid;
}
if (m_files[system_file_handle].refCount > 0) return FileFD.invalid;
m_files[system_file_handle] = FileInfo.init;
m_files[system_file_handle].refCount = 1;
@ -181,6 +186,8 @@ final class ThreadedFileEventDriver(Events : EventDriverEvents) : EventDriverFil
{
//assert(this.writable);
auto f = &m_files[file].write;
if (!safeCAS(f.status, ThreadedFileStatus.idle, ThreadedFileStatus.initiated))
assert(false, "Concurrent file writes are not allowed.");
assert(f.callback is null, "Concurrent file writes are not allowed.");
f.callback = on_write_finish;
m_activeWrites.insert(file);
@ -201,16 +208,20 @@ log("start task");
final override void cancelWrite(FileFD file)
{
assert(m_activeWrites.contains(file), "Cancelling write when no write is in progress.");
auto f = &m_files[file].write;
f.callback = null;
m_activeWrites.remove(file);
m_events.trigger(m_readyEvent, true); // ensure that no stale wait operation is left behind
auto res = () @trusted { return cas(&f.status, ThreadedFileStatus.processing, ThreadedFileStatus.cancelling); } ();
assert(res, "Cancelling write when no write is in progress.");
safeCAS(f.status, ThreadedFileStatus.processing, ThreadedFileStatus.cancelling);
}
final override void read(FileFD file, ulong offset, ubyte[] buffer, IOMode, FileIOCallback on_read_finish)
{
auto f = &m_files[file].read;
if (!safeCAS(f.status, ThreadedFileStatus.idle, ThreadedFileStatus.initiated))
assert(false, "Concurrent file writes are not allowed.");
assert(f.callback is null, "Concurrent file reads are not allowed.");
f.callback = on_read_finish;
m_activeReads.insert(file);
@ -230,11 +241,13 @@ log("start task");
final override void cancelRead(FileFD file)
{
assert(m_activeReads.contains(file), "Cancelling read when no read is in progress.");
auto f = &m_files[file].read;
f.callback = null;
m_activeReads.remove(file);
m_events.trigger(m_readyEvent, true); // ensure that no stale wait operation is left behind
auto res = () @trusted { return cas(&f.status, ThreadedFileStatus.processing, ThreadedFileStatus.cancelling); } ();
assert(res, "Cancelling read when no write is in progress.");
safeCAS(f.status, ThreadedFileStatus.processing, ThreadedFileStatus.cancelling);
}
final override void addRef(FileFD descriptor)
@ -260,22 +273,10 @@ log("start task");
{
log("task fun");
IOInfo* f = mixin("&fd.m_files[file]."~op);
log("wait for cancel");
// wait for previous cancel requests to finish
while (safeAtomicLoad(f.status) == ThreadedFileStatus.cancelling)
safeYield();
log("wait for callback");
// wait for previous callbacks to be fired
while (safeAtomicLoad(f.status).among(ThreadedFileStatus.finished, ThreadedFileStatus.cancelled))
safeYield();
assert(safeAtomicLoad(f.status) == ThreadedFileStatus.idle);
log("start processing");
auto res = safeCAS(f.status, ThreadedFileStatus.idle, ThreadedFileStatus.processing);
assert(res, "Concurrent file "~op~"s are disallowed.");
if (!safeCAS(f.status, ThreadedFileStatus.initiated, ThreadedFileStatus.processing))
assert(false, "File slot not in initiated state when processor task is started.");
auto bytes = buffer;
version (Windows) {
@ -303,7 +304,7 @@ log("check for cancel");
}
f.ioStatus = IOStatus.ok;
log("wait for status set");
while (true) {
if (safeCAS(f.status, ThreadedFileStatus.processing, ThreadedFileStatus.finished)) break;
@ -314,15 +315,11 @@ log("wait for status set");
private void onReady(EventID)
{
log("ready event");
foreach (f; m_activeReads) {
m_activeReads.remove(f);
m_files[f].read.flush(f);
}
foreach (f; m_activeReads)
m_files[f].read.finalize(f, { m_activeReads.remove(f); });
foreach (f; m_activeWrites) {
m_activeWrites.remove(f);
m_files[f].write.flush(f);
}
foreach (f; m_activeWrites)
m_files[f].write.finalize(f, { m_activeWrites.remove(f); });
m_waiting = false;
startWaiting();