On Wednesday 16 December 2009 13:35, David Greene wrote:
> > Please make BufferSize an 'unsigned' and default it to 8192.
Please use
> > PRESERVE_STREAM instead of 'false'.
Here's an updated version of the circular buffer. Ok to check in?
-Dave
Index: include/llvm/Support/circular_raw_ostream.h
==================================================================---
include/llvm/Support/circular_raw_ostream.h (revision 0)
+++ include/llvm/Support/circular_raw_ostream.h (revision 0)
@@ -0,0 +1,150 @@
+//===-- llvm/Support/circular_raw_ostream.h - Buffered streams --*- C++
-*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains raw_ostream implementations for streams to do circular
+// buffering of their output.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_CIRCULAR_RAW_OSTREAM_H
+#define LLVM_SUPPORT_CIRCULAR_RAW_OSTREAM_H
+
+#include "llvm/Support/raw_ostream.h"
+
+namespace llvm
+{
+ /// circular_raw_ostream - A raw_ostream that saves its output in a
+ /// circular buffer.
+ ///
+ class circular_raw_ostream : public raw_ostream {
+ public:
+ /// DELETE_STREAM - Tell the destructor to delete the held stream.
+ ///
+ static const bool DELETE_STREAM = true;
+
+ /// PRESERVE_STREAM - Tell the destructor to not delete the held
+ /// stream.
+ ///
+ static const bool PRESERVE_STREAM = false;
+
+ private:
+ /// TheStream - The real stream we output to. We set it to be
+ /// unbuffered, since we're already doing our own buffering.
+ ///
+ raw_ostream *TheStream;
+
+ /// DeleteStream - Do we need to delete TheStream in the
+ /// destructor?
+ ///
+ bool DeleteStream;
+
+ /// BufferSize - The size of the buffer in bytes.
+ ///
+ unsigned BufferSize;
+ /// BufferArray - The actual buffer storage.
+ ///
+ char *BufferArray;
+
+ /// Cur - Pointer to the current output point in BufferArray.
+ ///
+ char *Cur;
+
+ /// printLog - Dump the contents of the buffer to Stream.
+ ///
+ void printLog(void) {
+ TheStream->write(BufferArray, BufferSize);
+ Cur = BufferArray;
+ }
+
+ virtual void write_impl(const char *Ptr, size_t Size);
+
+ /// current_pos - Return the current position within the stream,
+ /// not counting the bytes currently in the buffer.
+ virtual uint64_t current_pos() {
+ // This has the same effect as calling TheStream.current_pos(),
+ // but that interface is private.
+ return TheStream->tell() - TheStream->GetNumBytesInBuffer();
+ }
+
+ public:
+ /// circular_raw_ostream - Open the specified file for
+ /// writing. If an error occurs, information about the error is
+ /// put into ErrorInfo, and the stream should be immediately
+ /// destroyed; the string will be empty if no error occurred.
+ ///
+ /// As a side effect, the given Stream is set to be Unbuffered.
+ /// This is because circular_raw_ostream does its own buffering,
+ /// so it doesn't want another layer of buffering to be happening
+ /// underneath it.
+ ///
+ circular_raw_ostream(raw_ostream &Stream, unsigned BuffSize = 8192,
+ bool Delete = false)
+ : raw_ostream(/*unbuffered*/true),
+ TheStream(0),
+ DeleteStream(PRESERVE_STREAM),
+ BufferSize(BuffSize),
+ BufferArray(0) {
+ if (BufferSize > 0)
+ BufferArray = new char[BufferSize];
+ Cur = BufferArray;
+ setStream(Stream, Delete);
+ }
+ explicit circular_raw_ostream()
+ : raw_ostream(/*unbuffered*/true),
+ TheStream(0),
+ DeleteStream(PRESERVE_STREAM),
+ BufferArray(0) {
+ Cur = BufferArray;
+ }
+
+ ~circular_raw_ostream() {
+ flush();
+ dumpLog();
+ releaseStream();
+ delete[] BufferArray;
+ }
+
+ void setStream(raw_ostream &Stream, bool Delete = false) {
+ releaseStream();
+
+ TheStream = &Stream;
+ DeleteStream = Delete;
+
+ if (BufferSize > 0) {
+ // This circular_raw_ostream will do its own buffering and it
+ // doesn't need or want TheStream to do another layer of
+ // buffering underneath. Tell TheStream not to do its own
+ // buffering.
+ TheStream->SetUnbuffered();
+ }
+ }
+
+ /// dumpLog - Force output of the buffer along with a small
+ /// header.
+ ///
+ void dumpLog(void);
+
+ private:
+ void releaseStream() {
+ // Delete the stream if needed. Otherwise, transfer the buffer
+ // settings from this raw_ostream back to the underlying stream.
+ if (!TheStream)
+ return;
+ if (DeleteStream)
+ delete TheStream;
+ else if (BufferSize > 0)
+ TheStream->SetBufferSize(BufferSize);
+ else
+ TheStream->SetUnbuffered();
+ }
+ };
+} // end llvm namespace
+
+
+#endif
Index: lib/Support/circular_raw_ostream.cpp
==================================================================---
lib/Support/circular_raw_ostream.cpp (revision 0)
+++ lib/Support/circular_raw_ostream.cpp (revision 0)
@@ -0,0 +1,45 @@
+//===- circulat_raw_ostream.cpp - Implement the circular_raw_ostream class
-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This implements support for circular buffered streams.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/circular_raw_ostream.h"
+
+using namespace llvm;
+
+void circular_raw_ostream::write_impl(const char *Ptr, size_t Size) {
+ if (BufferSize > 0) {
+ // Write into the buffer, wrapping if necessary.
+ while (Size > 0) {
+ while (Size > 0 && Cur != BufferArray + BufferSize) {
+ --Size;
+ *Cur++ = *Ptr++;
+ }
+ if (Cur == BufferArray + BufferSize)
+ // Reset the output pointer to the start of the buffer.
+ Cur = BufferArray;
+ }
+ }
+ else {
+ TheStream->write(Ptr, Size);
+ }
+}
+
+void circular_raw_ostream::dumpLog(void) {
+ if (BufferSize > 0) {
+ // Write out the buffer
+ const char *msg = "*** Log Output ***\n";
+ int num = std::strlen(msg);
+
+ TheStream->write(msg, num);
+ printLog();
+ }
+}