diff options
| -rw-r--r-- | generic/tclIO.c | 157 | ||||
| -rw-r--r-- | generic/tclIO.h | 5 | ||||
| -rw-r--r-- | tests/io.test | 4 |
3 files changed, 67 insertions, 99 deletions
diff --git a/generic/tclIO.c b/generic/tclIO.c index 9e1a723..0716074 100644 --- a/generic/tclIO.c +++ b/generic/tclIO.c @@ -284,7 +284,7 @@ static int WillRead(Channel *chanPtr); #define IsBufferEmpty(bufPtr) ((bufPtr)->nextAdded == (bufPtr)->nextRemoved) -#define IsBufferFull(bufPtr) ((bufPtr)->nextAdded >= (bufPtr)->bufLength) +#define IsBufferFull(bufPtr) ((bufPtr) && (bufPtr)->nextAdded >= (bufPtr)->bufLength) #define IsBufferOverflowing(bufPtr) ((bufPtr)->nextAdded > (bufPtr)->bufLength) @@ -1148,15 +1148,6 @@ Tcl_UnregisterChannel( */ if (statePtr->refCount <= 0) { - /* - * Ensure that if there is another buffer, it gets flushed whether or - * not we are doing a background flush. - */ - - if ((statePtr->curOutPtr != NULL) && - IsBufferReady(statePtr->curOutPtr)) { - SetFlag(statePtr, BUFFER_READY); - } Tcl_Preserve((ClientData)statePtr); if (!GotFlag(statePtr, BG_FLUSH_SCHEDULED)) { /* @@ -2490,8 +2481,6 @@ FlushChannel( ChannelState *statePtr = chanPtr->state; /* State of the channel stack. */ ChannelBuffer *bufPtr; /* Iterates over buffered output queue. */ - int toWrite; /* Amount of output data in current buffer - * available to be written. */ int written; /* Amount of output data actually written in * current round. */ int errorCode = 0; /* Stores POSIX error codes from channel @@ -2511,62 +2500,57 @@ FlushChannel( } /* - * Loop over the queued buffers and attempt to flush as much as possible - * of the queued output to the channel. + * Should we shift the current output buffer over to the output queue? + * First check that there are bytes in it. If so then... + * If the output queue is empty, then yes, trusting the caller called + * us only when written bytes ought to be flushed. + * If the current output buffer is full, then yes, so we can meet + * the post-condition that on a successful return to caller we've + * left space in the current output buffer for more writing (the flush + * call was to make new room). + * Otherwise, no. Keep the current output buffer where it is so more + * can be written to it, possibly filling it, to promote more efficient + * buffer usage. */ - while (1) { - /* - * If the queue is empty and there is a ready current buffer, OR if - * the current buffer is full, then move the current buffer to the - * queue. - */ - - if (((statePtr->curOutPtr != NULL) && - IsBufferFull(statePtr->curOutPtr)) - || (GotFlag(statePtr, BUFFER_READY) && - (statePtr->outQueueHead == NULL))) { - ResetFlag(statePtr, BUFFER_READY); - statePtr->curOutPtr->nextPtr = NULL; - if (statePtr->outQueueHead == NULL) { - statePtr->outQueueHead = statePtr->curOutPtr; - } else { - statePtr->outQueueTail->nextPtr = statePtr->curOutPtr; - } - statePtr->outQueueTail = statePtr->curOutPtr; - statePtr->curOutPtr = NULL; + bufPtr = statePtr->curOutPtr; + if (bufPtr && BytesLeft(bufPtr) && /* Keep empties off queue */ + (statePtr->outQueueHead == NULL || IsBufferFull(bufPtr))) { + if (statePtr->outQueueHead == NULL) { + statePtr->outQueueHead = bufPtr; + } else { + statePtr->outQueueTail->nextPtr = bufPtr; } - bufPtr = statePtr->outQueueHead; + statePtr->outQueueTail = bufPtr; + statePtr->curOutPtr = NULL; + } - /* - * If we are not being called from an async flush and an async flush - * is active, we just return without producing any output. - */ + assert(!IsBufferFull(statePtr->curOutPtr)); - if (!calledFromAsyncFlush && GotFlag(statePtr, BG_FLUSH_SCHEDULED)) { - return 0; - } + /* + * If we are not being called from an async flush and an async flush + * is active, we just return without producing any output. + */ - /* - * If the output queue is still empty, break out of the while loop. - */ + if (!calledFromAsyncFlush && GotFlag(statePtr, BG_FLUSH_SCHEDULED)) { + return 0; + } - if (bufPtr == NULL) { - break; /* Out of the "while (1)". */ - } + /* + * Loop over the queued buffers and attempt to flush as much as possible + * of the queued output to the channel. + */ + + while (statePtr->outQueueHead) { + bufPtr = statePtr->outQueueHead; /* * Produce the output on the channel. */ PreserveChannelBuffer(bufPtr); - toWrite = BytesLeft(bufPtr); - if (toWrite == 0) { - written = 0; - } else { - written = (chanPtr->typePtr->outputProc)(chanPtr->instanceData, - RemovePoint(bufPtr), toWrite, &errorCode); - } + written = (chanPtr->typePtr->outputProc)(chanPtr->instanceData, + RemovePoint(bufPtr), BytesLeft(bufPtr), &errorCode); /* * If the write failed completely attempt to start the asynchronous @@ -2672,8 +2656,10 @@ FlushChannel( DiscardOutputQueued(statePtr); ReleaseChannelBuffer(bufPtr); - continue; + break; } else { + /* TODO: Consider detecting and reacting to short writes + * on blocking channels. Ought not happen. See iocmd-24.2. */ wroteSome = 1; } @@ -2691,7 +2677,7 @@ FlushChannel( RecycleBuffer(statePtr, bufPtr, 0); } ReleaseChannelBuffer(bufPtr); - } /* Closes "while (1)". */ + } /* Closes "while". */ /* * If we wrote some data while flushing in the background, we are done. @@ -2707,6 +2693,12 @@ FlushChannel( ResetFlag(statePtr, BG_FLUSH_SCHEDULED); (chanPtr->typePtr->watchProc)(chanPtr->instanceData, statePtr->interestMask); + } else { + /* TODO: If code reaches this point, it means a writable + * event is being handled on the channel, but the channel + * could not in fact be written to. This ought not happen, + * but Unix pipes appear to act this way (see io-53.4). + * Also can imagine broken reflected channels. */ } } @@ -3252,14 +3244,6 @@ Tcl_Close( ResetFlag(statePtr, CHANNEL_INCLOSE); /* - * Ensure that the last output buffer will be flushed. - */ - - if ((statePtr->curOutPtr != NULL) && IsBufferReady(statePtr->curOutPtr)) { - SetFlag(statePtr, BUFFER_READY); - } - - /* * If this channel supports it, close the read side, since we don't need * it anymore and this will help avoid deadlocks on some channel types. */ @@ -3669,10 +3653,17 @@ static int WillRead(Channel *chanPtr) } if ((chanPtr->typePtr->seekProc != NULL) && (Tcl_OutputBuffered((Tcl_Channel) chanPtr) > 0)) { - if ((chanPtr->state->curOutPtr != NULL) - && IsBufferReady(chanPtr->state->curOutPtr)) { - SetFlag(chanPtr->state, BUFFER_READY); - } + + /* + * CAVEAT - The assumption here is that FlushChannel() will + * push out the bytes of any writes that are in progress. + * Since this is a seekable channel, we assume it is not one + * that can block and force bg flushing. Channels we know that + * can do that -- sockets, pipes -- are not seekable. If the + * assumption is wrong, more drastic measures may be required here + * like temporarily setting the channel into blocking mode. + */ + if (FlushChannel(NULL, chanPtr, 0) != 0) { return -1; } @@ -3854,7 +3845,6 @@ Write( } if ((flushed < total) && (GotFlag(statePtr, CHANNEL_UNBUFFERED) || (needNlFlush && GotFlag(statePtr, CHANNEL_LINEBUFFERED)))) { - SetFlag(statePtr, BUFFER_READY); if (FlushChannel(NULL, chanPtr, 0) != 0) { return -1; } @@ -5973,14 +5963,6 @@ Tcl_Flush( return -1; } - /* - * Force current output buffer to be output also. - */ - - if ((statePtr->curOutPtr != NULL) && IsBufferReady(statePtr->curOutPtr)) { - SetFlag(statePtr, BUFFER_READY); - } - result = FlushChannel(NULL, chanPtr, 0); if (result != 0) { return TCL_ERROR; @@ -6120,9 +6102,8 @@ GetInput( */ bufPtr = statePtr->inQueueTail; - if ((bufPtr != NULL) && !IsBufferFull(bufPtr)) { - toRead = SpaceLeft(bufPtr); - } else { + + if ((bufPtr == NULL) || IsBufferFull(bufPtr)) { bufPtr = statePtr->saveInBufPtr; statePtr->saveInBufPtr = NULL; @@ -6152,6 +6133,8 @@ GetInput( statePtr->inQueueTail->nextPtr = bufPtr; } statePtr->inQueueTail = bufPtr; + } else { + toRead = SpaceLeft(bufPtr); } PreserveChannelBuffer(bufPtr); @@ -6293,15 +6276,6 @@ Tcl_Seek( } /* - * If there is data buffered in statePtr->curOutPtr then mark the channel - * as ready to flush before invoking FlushChannel. - */ - - if ((statePtr->curOutPtr != NULL) && IsBufferReady(statePtr->curOutPtr)) { - SetFlag(statePtr, BUFFER_READY); - } - - /* * If the flush fails we cannot recover the original position. In that * case the seek is not attempted because we do not know where the access * position is - instead we return the error. FlushChannel has already @@ -8825,7 +8799,7 @@ DoRead( /* If there is no full buffer, attempt to create and/or fill one. */ - while (bufPtr == NULL || !IsBufferFull(bufPtr)) { + while (!IsBufferFull(bufPtr)) { int code; moreData: @@ -10380,7 +10354,6 @@ DumpFlags( ChanFlag('n', CHANNEL_NONBLOCKING); ChanFlag('l', CHANNEL_LINEBUFFERED); ChanFlag('u', CHANNEL_UNBUFFERED); - ChanFlag('R', BUFFER_READY); ChanFlag('F', BG_FLUSH_SCHEDULED); ChanFlag('c', CHANNEL_CLOSED); ChanFlag('E', CHANNEL_EOF); diff --git a/generic/tclIO.h b/generic/tclIO.h index b8fb5be..59182ec 100644 --- a/generic/tclIO.h +++ b/generic/tclIO.h @@ -227,11 +227,6 @@ typedef struct ChannelState { * flushed after every newline. */ #define CHANNEL_UNBUFFERED (1<<5) /* Output to the channel must always * be flushed immediately. */ -#define BUFFER_READY (1<<6) /* Current output buffer (the - * curOutPtr field in the channel - * structure) should be output as soon - * as possible even though it may not - * be full. */ #define BG_FLUSH_SCHEDULED (1<<7) /* A background flush of the queued * output buffers has been * scheduled. */ diff --git a/tests/io.test b/tests/io.test index c7da8e6..f1248b9 100644 --- a/tests/io.test +++ b/tests/io.test @@ -2786,7 +2786,7 @@ test io-29.34 {Tcl_Close, async flush on close, using sockets} {socket tempNotMa variable x running set l abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz proc writelots {s l} { - for {set i 0} {$i < 2000} {incr i} { + for {set i 0} {$i < 9000} {incr i} { puts $s $l } } @@ -2817,7 +2817,7 @@ test io-29.34 {Tcl_Close, async flush on close, using sockets} {socket tempNotMa close $ss vwait [namespace which -variable x] set c -} 2000 +} 9000 test io-29.35 {Tcl_Close vs fileevent vs multiple interpreters} {socket tempNotMac fileevent} { # On Mac, this test screws up sockets such that subsequent tests using port 2828 # either cause errors or panic(). |