eventcore/source/eventcore/drivers/threadedfile.d
Sönke Ludwig c4550f0e59
Fix ThreadedFileEventDriver read/write issues.
I/O errors were being reported as IOStatus.ok instead of IOStatus.error, and the I/O operation finalization protocol had a potential race-condition when storing the number of bytes processed.
2017-10-30 22:54:14 +01:00

362 lines
10 KiB
D

module eventcore.drivers.threadedfile;
import eventcore.driver;
import eventcore.internal.utils;
import core.atomic;
import core.stdc.errno;
import std.algorithm.comparison : among, min;
version(Posix){
import core.sys.posix.fcntl;
import core.sys.posix.sys.stat;
import core.sys.posix.unistd;
}
version(Windows){
static if (__VERSION__ >= 2070)
import core.sys.windows.stat;
else
import std.c.windows.stat;
private {
// TODO: use CreateFile/HANDLE instead of the Posix API on Windows
extern(C) nothrow {
alias off_t = sizediff_t;
int open(in char* name, int mode, ...);
int chmod(in char* name, int mode);
int close(int fd) @safe;
int read(int fd, void *buffer, uint count);
int write(int fd, in void *buffer, uint count);
off_t lseek(int fd, off_t offset, int whence) @safe;
}
enum O_RDONLY = 0;
enum O_WRONLY = 1;
enum O_RDWR = 2;
enum O_APPEND = 8;
enum O_CREAT = 0x0100;
enum O_TRUNC = 0x0200;
enum O_BINARY = 0x8000;
enum _S_IREAD = 0x0100; /* read permission, owner */
enum _S_IWRITE = 0x0080; /* write permission, owner */
alias stat_t = struct_stat;
}
}
else
{
enum O_BINARY = 0;
}
private {
enum SEEK_SET = 0;
enum SEEK_CUR = 1;
enum SEEK_END = 2;
}
final class ThreadedFileEventDriver(Events : EventDriverEvents) : EventDriverFiles
{
import std.parallelism;
private {
enum ThreadedFileStatus {
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 {
FileIOCallback callback;
shared ThreadedFileStatus status;
shared size_t bytesWritten;
shared IOStatus ioStatus;
void finalize(FileFD fd, scope void delegate() @safe nothrow pre_cb)
@safe nothrow {
auto st = safeAtomicLoad(this.status);
if (st == ThreadedFileStatus.finished) {
auto ios = safeAtomicLoad(this.ioStatus);
auto btw = safeAtomicLoad(this.bytesWritten);
auto cb = this.callback;
this.callback = null;
safeAtomicStore(this.status, ThreadedFileStatus.idle);
pre_cb();
if (cb) {
log("fire callback");
cb(fd, ios, btw);
}
} else if (st == ThreadedFileStatus.cancelled) {
this.callback = null;
safeAtomicStore(this.status, ThreadedFileStatus.idle);
pre_cb();
log("ignore callback due to cancellation");
}
}
}
static struct FileInfo {
IOInfo read;
IOInfo write;
int refCount;
}
TaskPool m_fileThreadPool;
ChoppedVector!FileInfo m_files;
SmallIntegerSet!FileFD m_activeReads;
SmallIntegerSet!FileFD m_activeWrites;
EventID m_readyEvent;
bool m_waiting;
Events m_events;
}
@safe: nothrow:
this(Events events)
{
m_events = events;
m_readyEvent = events.create();
}
void dispose()
{
if (m_fileThreadPool) {
log("finishing thread pool");
try m_fileThreadPool.finish();
catch (Exception e) {
//logError("Failed to shut down file I/O thread pool.");
}
}
log("finishing file events");
m_events.cancelWait(m_readyEvent, &onReady);
onReady(m_readyEvent);
m_events.releaseRef(m_readyEvent);
log("finished file events");
}
final override FileFD open(string path, FileOpenMode mode)
{
import std.string : toStringz;
import std.conv : octal;
int flags;
int amode;
final switch (mode) {
case FileOpenMode.read: flags = O_RDONLY|O_BINARY; break;
case FileOpenMode.readWrite: flags = O_RDWR|O_BINARY; break;
case FileOpenMode.createTrunc: flags = O_RDWR|O_CREAT|O_TRUNC|O_BINARY; amode = octal!644; break;
case FileOpenMode.append: flags = O_WRONLY|O_CREAT|O_APPEND|O_BINARY; amode = octal!644; break;
}
auto fd = () @trusted { return .open(path.toStringz(), flags, amode); } ();
if (fd < 0) return FileFD.init;
return adopt(fd);
}
final override FileFD adopt(int system_file_handle)
{
version (Windows) {
// TODO: check if FD is a valid file!
} else {
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;
return FileFD(system_file_handle);
}
void close(FileFD file)
{
() @trusted { .close(cast(int)file); } ();
}
ulong getSize(FileFD file)
{
version (linux) {
// stat_t seems to be defined wrong on linux/64
return .lseek(cast(int)file, 0, SEEK_END);
} else {
stat_t st;
() @trusted { fstat(cast(int)file, &st); } ();
return st.st_size;
}
}
final override void write(FileFD file, ulong offset, const(ubyte)[] buffer, IOMode, FileIOCallback on_write_finish)
{
//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);
log("start task");
try {
if (m_fileThreadPool is null) {
m_fileThreadPool = new TaskPool(4);
m_fileThreadPool.isDaemon = true;
}
m_fileThreadPool.put(task!(taskFun!("write", const(ubyte)))(this, file, offset, buffer));
startWaiting();
} catch (Exception e) {
m_activeWrites.remove(file);
on_write_finish(file, IOStatus.error, 0);
return;
}
}
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
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 reads are not allowed.");
assert(f.callback is null, "Concurrent file reads are not allowed.");
f.callback = on_read_finish;
m_activeReads.insert(file);
try {
if (m_fileThreadPool is null) {
m_fileThreadPool = new TaskPool(4);
m_fileThreadPool.isDaemon = true;
}
m_fileThreadPool.put(task!(taskFun!("read", ubyte))(this, file, offset, buffer));
startWaiting();
} catch (Exception e) {
m_activeReads.remove(file);
on_read_finish(file, IOStatus.error, 0);
return;
}
}
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
safeCAS(f.status, ThreadedFileStatus.processing, ThreadedFileStatus.cancelling);
}
final override void addRef(FileFD descriptor)
{
m_files[descriptor].refCount++;
}
final override bool releaseRef(FileFD descriptor)
{
auto f = () @trusted { return &m_files[descriptor]; } ();
if (!--f.refCount) {
.close(cast(int)descriptor);
*f = FileInfo.init;
assert(!m_activeReads.contains(descriptor));
assert(!m_activeWrites.contains(descriptor));
return false;
}
return true;
}
/// private
static void taskFun(string op, UB)(ThreadedFileEventDriver fd, FileFD file, ulong offset, UB[] buffer)
{
log("task fun");
IOInfo* f = mixin("&fd.m_files[file]."~op);
log("start processing");
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) {
assert(offset <= off_t.max);
.lseek(cast(int)file, cast(off_t)offset, SEEK_SET);
} else .lseek(cast(int)file, offset, SEEK_SET);
scope (exit) {
log("trigger event");
() @trusted { return cast(shared)fd.m_events; } ().trigger(fd.m_readyEvent, true);
}
if (bytes.length == 0) safeAtomicStore(f.ioStatus, IOStatus.ok);
while (bytes.length > 0) {
auto sz = min(bytes.length, 4096);
auto ret = () @trusted { return mixin("."~op)(cast(int)file, bytes.ptr, cast(uint)sz); } ();
if (ret != sz) {
safeAtomicStore(f.ioStatus, IOStatus.error);
log("error");
break;
}
bytes = bytes[sz .. $];
log("check for cancel");
if (safeCAS(f.status, ThreadedFileStatus.cancelling, ThreadedFileStatus.cancelled)) return;
}
safeAtomicStore(f.bytesWritten, buffer.length - bytes.length);
log("wait for status set");
while (true) {
if (safeCAS(f.status, ThreadedFileStatus.processing, ThreadedFileStatus.finished)) break;
if (safeCAS(f.status, ThreadedFileStatus.cancelling, ThreadedFileStatus.cancelled)) break;
}
}
private void onReady(EventID)
{
log("ready event");
foreach (f; m_activeReads)
m_files[f].read.finalize(f, { m_activeReads.remove(f); });
foreach (f; m_activeWrites)
m_files[f].write.finalize(f, { m_activeWrites.remove(f); });
m_waiting = false;
startWaiting();
}
private void startWaiting()
{
if (!m_waiting && (!m_activeWrites.empty || !m_activeReads.empty)) {
log("wait for ready");
m_events.wait(m_readyEvent, &onReady);
m_waiting = true;
}
}
}
private auto safeAtomicLoad(T)(ref shared(T) v) @trusted { return atomicLoad(v); }
private auto safeAtomicStore(T)(ref shared(T) v, T a) @trusted { return atomicStore(v, a); }
private auto safeCAS(T, U, V)(ref shared(T) v, U a, V b) @trusted { return cas(&v, a, b); }
private void safeYield() @trusted nothrow {
import core.thread : Thread;
import core.time : seconds;
Thread.sleep(0.seconds);
}
private void log(ARGS...)(string fmt, ARGS args)
@trusted nothrow {
debug (EventCoreLogFiles) {
scope (failure) assert(false);
import core.thread : Thread;
import std.stdio : writef, writefln;
writef("[%s] ", Thread.getThis().name);
writefln(fmt, args);
}
}