diff options
Diffstat (limited to 'generic')
| -rw-r--r-- | generic/tclIO.c | 114 | ||||
| -rw-r--r-- | generic/tclIO.h | 5 |
2 files changed, 38 insertions, 81 deletions
diff --git a/generic/tclIO.c b/generic/tclIO.c index 17efa1e..911fa97 100644 --- a/generic/tclIO.c +++ b/generic/tclIO.c @@ -1149,15 +1149,6 @@ 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)) { /* @@ -2491,8 +2482,6 @@ 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 @@ -2511,36 +2500,42 @@ FlushChannel( return -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. - */ + /* + * 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. + */ - if (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; } + statePtr->outQueueTail = bufPtr; + statePtr->curOutPtr = NULL; + } assert(!IsBufferFull(statePtr->curOutPtr)); - /* - * If we are not being called from an async flush and an async flush - * is active, we just return without producing any output. - */ + /* + * If we are not being called from an async flush and an async flush + * is active, we just return without producing any output. + */ - if (!calledFromAsyncFlush && GotFlag(statePtr, BG_FLUSH_SCHEDULED)) { - return 0; - } + if (!calledFromAsyncFlush && GotFlag(statePtr, BG_FLUSH_SCHEDULED)) { + return 0; + } /* * Loop over the queued buffers and attempt to flush as much as possible @@ -2555,14 +2550,8 @@ FlushChannel( */ PreserveChannelBuffer(bufPtr); - toWrite = BytesLeft(bufPtr); - if (toWrite == 0) { - /* TODO: This cannot happen. */ - 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 @@ -2668,7 +2657,7 @@ 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. */ @@ -2689,7 +2678,7 @@ 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. @@ -3256,14 +3245,6 @@ 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. */ @@ -3673,10 +3654,10 @@ 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); - } + + /* TODO: Consider when channel is nonblocking and this + * FlushChannel() call may not finish the task of shoving + * bytes out. Then what? */ if (FlushChannel(NULL, chanPtr, 0) != 0) { return -1; } @@ -3858,7 +3839,6 @@ 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; } @@ -5977,14 +5957,6 @@ 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; @@ -6298,15 +6270,6 @@ 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 @@ -10385,7 +10348,6 @@ 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. */ |