fixes bug 146884 - Mozilla sometimes consumes 100% CPU when pipelining is enabled...

r=dougt sr=rpotts a=asa

netwerk/base/src/nsSocketTransport.cpp

@@ -2935,6 +2935,13 @@ nsSocketReadRequest::OnRead()
     // Allow reads beyond what is available right now.
     amount = MAX_IO_TRANSFER_SIZE;
 
+    // Since the input stream remembers any socket errors, we need to
+    // be sure to clear the error state before calling OnDataAvailable.
+    // If we don't, and the listener fails to call the Read method on
+    // mInputStream, then GotWouldBlock() might incorrectly return TRUE,
+    // which could lead us to loop indefinitely (See bug 146884).
+    mInputStream->ClearError();
+
     LOG(("nsSocketReadRequest: [this=%x] calling listener [offset=%u, count=%u]\n",
         this, offset, amount));
 
@@ -3038,6 +3045,13 @@ nsSocketWriteRequest::OnWrite()
     nsresult rv;
     PRUint32 offset = mOutputStream->GetOffset();
 
+    // Since the output stream remembers any socket errors, we need to
+    // be sure to clear the error state before calling OnDataWritable.
+    // If we don't, and the provider fails to call the Write method on
+    // mOutputStream, then GotWouldBlock() might incorrectly return TRUE,
+    // which could lead us to loop indefinitely (See bug 146884).
+    mOutputStream->ClearError();
+
     rv = mProvider->OnDataWritable(this,
                                    mContext,
                                    mOutputStream,

netwerk/base/src/nsSocketTransport.h

@@ -386,6 +386,7 @@ public:
     PRBool      GotWouldBlock() { return mError == PR_WOULD_BLOCK_ERROR; }
     PRBool      GotError() { return mError != 0; }
     PRErrorCode GetError() { return mError; }
+    void        ClearError() { mError = 0; }
 
 private:
     PRUint32    mOffset;
@@ -413,6 +414,7 @@ public:
     PRBool      GotWouldBlock() { return mError == PR_WOULD_BLOCK_ERROR; }
     PRBool      GotError() { return mError != 0; }
     PRErrorCode GetError() { return mError; }
+    void        ClearError() { mError = 0; }
 
 private:
     static NS_METHOD WriteFromSegments(nsIInputStream *, void *, const char *,

netwerk/protocol/http/src/nsHttpPipeline.cpp

@@ -439,13 +439,22 @@ nsHttpPipeline::OnDataWritable(nsIOutputStream *stream)
             // maybe this transaction has already been canceled...
             if (mTransactionQ[i]) {
                 while (1) {
+                    PRUint32 before = 0, after = 0;
+                    mRequestData->Available(&before);
+                    // append the transaction's request data to our buffer...
                     rv = mTransactionQ[i]->OnDataWritable(outputStream);
                     if (rv == NS_BASE_STREAM_CLOSED)
                         break; // advance to next transaction
                     if (NS_FAILED(rv))
                         return rv; // something bad happened!!
                     // else, there's more to write (the transaction may be
-                    // writing in small chunks).
+                    // writing in small chunks).  verify that the transaction
+                    // actually wrote something to the pipe, and if it didn't,
+                    // then advance to the next transaction to avoid an
+                    // infinite loop (see bug 146884).
+                    mRequestData->Available(&after);
+                    if (before == after)
+                        break;
                 }
             }
         }