From 12e1853a3e592b7d9033691f7460ecfc95ce8ac6 Mon Sep 17 00:00:00 2001
From: "dgp@users.sourceforge.net" <dgp>
Date: Thu, 21 Aug 2014 23:07:34 +0000
Subject: Test fix for likely cause of reported I/O slowdown. In a DoRead()
 revision, it came to favor making every effort to fill buffers, in preference
 to a more sensible goal of favoring avoiding calls out to the driver if
 there's already enough data in the buffers to satisfy the read operation. 
 Result is many more calls out to recv() than are a good idea.  Ought to show
 up most glaringly when many Tcl_Read() calls asking for small numbers of
 bytes (compared to buffer size) each, and that matches the reported case.

---
 generic/tclIO.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/generic/tclIO.c b/generic/tclIO.c
index 4452ae9..4f81770 100644
--- a/generic/tclIO.c
+++ b/generic/tclIO.c
@@ -8855,6 +8855,7 @@ DoRead(
 
 	/* If there is no full buffer, attempt to create and/or fill one. */
 
+if (bufPtr == NULL || BytesLeft(bufPtr) < bytesToRead) {
 	while (!IsBufferFull(bufPtr)) {
 	    int code;
 
@@ -8880,6 +8881,7 @@ DoRead(
 	}
 
 	assert (bufPtr != NULL);
+}
 
 	bytesRead = BytesLeft(bufPtr);
 	bytesWritten = bytesToRead;
-- 
cgit v0.12


From 86660354ac032346d34dff024b9f4c9cf38d4148 Mon Sep 17 00:00:00 2001
From: "dgp@users.sourceforge.net" <dgp>
Date: Fri, 22 Aug 2014 13:20:21 +0000
Subject: Same results; simpler logic.

---
 generic/tclIO.c | 28 +++++++---------------------
 1 file changed, 7 insertions(+), 21 deletions(-)

diff --git a/generic/tclIO.c b/generic/tclIO.c
index 4f81770..93ac937 100644
--- a/generic/tclIO.c
+++ b/generic/tclIO.c
@@ -8853,36 +8853,22 @@ DoRead(
 	    break;
 	}
 
-	/* If there is no full buffer, attempt to create and/or fill one. */
-
-if (bufPtr == NULL || BytesLeft(bufPtr) < bytesToRead) {
-	while (!IsBufferFull(bufPtr)) {
-	    int code;
+	/*
+	 * If there is not enough data in the buffers to possibly
+	 * complete the read, then go get more.
+	 */
 
+	if (bufPtr == NULL || BytesLeft(bufPtr) < bytesToRead) {
 	moreData:
-	    code = GetInput(chanPtr);
-	    bufPtr = statePtr->inQueueHead;
-
-	    assert (bufPtr != NULL);
-
-	    if (GotFlag(statePtr, CHANNEL_EOF|CHANNEL_BLOCKED)) {
-		/* Further reads cannot do any more */
-		break;
-	    }
-	    
-	    if (code) {
+	    if (GetInput(chanPtr)) {
 		/* Read error */
 		UpdateInterest(chanPtr);
 		TclChannelRelease((Tcl_Channel)chanPtr);
 		return -1;
 	    }
-
-	    assert (IsBufferFull(bufPtr));
+	    bufPtr = statePtr->inQueueHead;
 	}
 
-	assert (bufPtr != NULL);
-}
-
 	bytesRead = BytesLeft(bufPtr);
 	bytesWritten = bytesToRead;
 
-- 
cgit v0.12