gecko-dev/xpcom/io/nsStorageStream.cpp

563 lines
17 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* vim:set ts=4 sts=4 sw=4 cin et: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Communicator client code, released
* March 31, 1998.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998-1999
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Pierre Phaneuf <pp@ludusdesign.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* The storage stream provides an internal buffer that can be filled by a
* client using a single output stream. One or more independent input streams
* can be created to read the data out non-destructively. The implementation
* uses a segmented buffer internally to avoid realloc'ing of large buffers,
* with the attendant performance loss and heap fragmentation.
*/
#include "nsAlgorithm.h"
#include "nsStorageStream.h"
#include "nsSegmentedBuffer.h"
#include "nsStreamUtils.h"
#include "nsCOMPtr.h"
#include "prbit.h"
#include "nsIInputStream.h"
#include "nsISeekableStream.h"
#include "prlog.h"
#if defined(PR_LOGGING)
//
// Log module for StorageStream logging...
//
// To enable logging (see prlog.h for full details):
//
// set NSPR_LOG_MODULES=StorageStreamLog:5
// set NSPR_LOG_FILE=nspr.log
//
// this enables PR_LOG_DEBUG level information and places all output in
// the file nspr.log
//
static PRLogModuleInfo* sLog = PR_NewLogModule("nsStorageStream");
#endif
#define LOG(args) PR_LOG(sLog, PR_LOG_DEBUG, args)
nsStorageStream::nsStorageStream()
: mSegmentedBuffer(0), mSegmentSize(0), mWriteInProgress(PR_FALSE),
mLastSegmentNum(-1), mWriteCursor(0), mSegmentEnd(0), mLogicalLength(0)
{
LOG(("Creating nsStorageStream [%p].\n", this));
}
nsStorageStream::~nsStorageStream()
{
delete mSegmentedBuffer;
}
NS_IMPL_THREADSAFE_ISUPPORTS2(nsStorageStream,
nsIStorageStream,
nsIOutputStream)
NS_IMETHODIMP
nsStorageStream::Init(PRUint32 segmentSize, PRUint32 maxSize,
nsIMemory *segmentAllocator)
{
mSegmentedBuffer = new nsSegmentedBuffer();
if (!mSegmentedBuffer)
return NS_ERROR_OUT_OF_MEMORY;
mSegmentSize = segmentSize;
mSegmentSizeLog2 = PR_FloorLog2(segmentSize);
// Segment size must be a power of two
if (mSegmentSize != ((PRUint32)1 << mSegmentSizeLog2))
return NS_ERROR_INVALID_ARG;
return mSegmentedBuffer->Init(segmentSize, maxSize, segmentAllocator);
}
NS_IMETHODIMP
nsStorageStream::GetOutputStream(PRInt32 aStartingOffset,
nsIOutputStream * *aOutputStream)
{
NS_ENSURE_ARG(aOutputStream);
NS_ENSURE_TRUE(mSegmentedBuffer, NS_ERROR_NOT_INITIALIZED);
if (mWriteInProgress)
return NS_ERROR_NOT_AVAILABLE;
nsresult rv = Seek(aStartingOffset);
if (NS_FAILED(rv)) return rv;
// Enlarge the last segment in the buffer so that it is the same size as
// all the other segments in the buffer. (It may have been realloc'ed
// smaller in the Close() method.)
if (mLastSegmentNum >= 0)
mSegmentedBuffer->ReallocLastSegment(mSegmentSize);
// Need to re-Seek, since realloc might have changed segment base pointer
rv = Seek(aStartingOffset);
if (NS_FAILED(rv)) return rv;
NS_ADDREF(this);
*aOutputStream = static_cast<nsIOutputStream*>(this);
mWriteInProgress = PR_TRUE;
return NS_OK;
}
NS_IMETHODIMP
nsStorageStream::Close()
{
NS_ENSURE_TRUE(mSegmentedBuffer, NS_ERROR_NOT_INITIALIZED);
mWriteInProgress = PR_FALSE;
PRInt32 segmentOffset = SegOffset(mLogicalLength);
// Shrink the final segment in the segmented buffer to the minimum size
// needed to contain the data, so as to conserve memory.
if (segmentOffset)
mSegmentedBuffer->ReallocLastSegment(segmentOffset);
mWriteCursor = 0;
mSegmentEnd = 0;
LOG(("nsStorageStream [%p] Close mWriteCursor=%x mSegmentEnd=%x\n",
this, mWriteCursor, mSegmentEnd));
return NS_OK;
}
NS_IMETHODIMP
nsStorageStream::Flush()
{
return NS_OK;
}
NS_IMETHODIMP
nsStorageStream::Write(const char *aBuffer, PRUint32 aCount, PRUint32 *aNumWritten)
{
NS_ENSURE_TRUE(mSegmentedBuffer, NS_ERROR_NOT_INITIALIZED);
const char* readCursor;
PRUint32 count, availableInSegment, remaining;
nsresult rv = NS_OK;
NS_ENSURE_ARG_POINTER(aNumWritten);
NS_ENSURE_ARG(aBuffer);
LOG(("nsStorageStream [%p] Write mWriteCursor=%x mSegmentEnd=%x aCount=%d\n",
this, mWriteCursor, mSegmentEnd, aCount));
remaining = aCount;
readCursor = aBuffer;
// If no segments have been created yet, create one even if we don't have
// to write any data; this enables creating an input stream which reads from
// the very end of the data for any amount of data in the stream (i.e.
// this stream contains N bytes of data and newInputStream(N) is called),
// even for N=0 (with the caveat that we require .write("", 0) be called to
// initialize internal buffers).
PRBool firstTime = mSegmentedBuffer->GetSegmentCount() == 0;
while (remaining || NS_UNLIKELY(firstTime)) {
firstTime = PR_FALSE;
availableInSegment = mSegmentEnd - mWriteCursor;
if (!availableInSegment) {
mWriteCursor = mSegmentedBuffer->AppendNewSegment();
if (!mWriteCursor) {
mSegmentEnd = 0;
rv = NS_ERROR_OUT_OF_MEMORY;
goto out;
}
mLastSegmentNum++;
mSegmentEnd = mWriteCursor + mSegmentSize;
availableInSegment = mSegmentEnd - mWriteCursor;
LOG(("nsStorageStream [%p] Write (new seg) mWriteCursor=%x mSegmentEnd=%x\n",
this, mWriteCursor, mSegmentEnd));
}
count = NS_MIN(availableInSegment, remaining);
memcpy(mWriteCursor, readCursor, count);
remaining -= count;
readCursor += count;
mWriteCursor += count;
LOG(("nsStorageStream [%p] Writing mWriteCursor=%x mSegmentEnd=%x count=%d\n",
this, mWriteCursor, mSegmentEnd, count));
};
out:
*aNumWritten = aCount - remaining;
mLogicalLength += *aNumWritten;
LOG(("nsStorageStream [%p] Wrote mWriteCursor=%x mSegmentEnd=%x numWritten=%d\n",
this, mWriteCursor, mSegmentEnd, *aNumWritten));
return rv;
}
NS_IMETHODIMP
nsStorageStream::WriteFrom(nsIInputStream *inStr, PRUint32 count, PRUint32 *_retval)
{
return NS_ERROR_NOT_IMPLEMENTED;
}
NS_IMETHODIMP
nsStorageStream::WriteSegments(nsReadSegmentFun reader, void * closure, PRUint32 count, PRUint32 *_retval)
{
return NS_ERROR_NOT_IMPLEMENTED;
}
NS_IMETHODIMP
nsStorageStream::IsNonBlocking(PRBool *aNonBlocking)
{
*aNonBlocking = PR_TRUE;
return NS_OK;
}
NS_IMETHODIMP
nsStorageStream::GetLength(PRUint32 *aLength)
{
NS_ENSURE_ARG(aLength);
*aLength = mLogicalLength;
return NS_OK;
}
// Truncate the buffer by deleting the end segments
NS_IMETHODIMP
nsStorageStream::SetLength(PRUint32 aLength)
{
NS_ENSURE_TRUE(mSegmentedBuffer, NS_ERROR_NOT_INITIALIZED);
if (mWriteInProgress)
return NS_ERROR_NOT_AVAILABLE;
if (aLength > mLogicalLength)
return NS_ERROR_INVALID_ARG;
PRInt32 newLastSegmentNum = SegNum(aLength);
PRInt32 segmentOffset = SegOffset(aLength);
if (segmentOffset == 0)
newLastSegmentNum--;
while (newLastSegmentNum < mLastSegmentNum) {
mSegmentedBuffer->DeleteLastSegment();
mLastSegmentNum--;
}
mLogicalLength = aLength;
return NS_OK;
}
NS_IMETHODIMP
nsStorageStream::GetWriteInProgress(PRBool *aWriteInProgress)
{
NS_ENSURE_ARG(aWriteInProgress);
*aWriteInProgress = mWriteInProgress;
return NS_OK;
}
NS_METHOD
nsStorageStream::Seek(PRInt32 aPosition)
{
NS_ENSURE_TRUE(mSegmentedBuffer, NS_ERROR_NOT_INITIALIZED);
// An argument of -1 means "seek to end of stream"
if (aPosition == -1)
aPosition = mLogicalLength;
// Seeking beyond the buffer end is illegal
if ((PRUint32)aPosition > mLogicalLength)
return NS_ERROR_INVALID_ARG;
// Seeking backwards in the write stream results in truncation
SetLength(aPosition);
// Special handling for seek to start-of-buffer
if (aPosition == 0) {
mWriteCursor = 0;
mSegmentEnd = 0;
LOG(("nsStorageStream [%p] Seek mWriteCursor=%x mSegmentEnd=%x\n",
this, mWriteCursor, mSegmentEnd));
return NS_OK;
}
// Segment may have changed, so reset pointers
mWriteCursor = mSegmentedBuffer->GetSegment(mLastSegmentNum);
NS_ASSERTION(mWriteCursor, "null mWriteCursor");
mSegmentEnd = mWriteCursor + mSegmentSize;
// Adjust write cursor for current segment offset. This test is necessary
// because SegNum may reference the next-to-be-allocated segment, in which
// case we need to be pointing at the end of the last segment.
PRInt32 segmentOffset = SegOffset(aPosition);
if (segmentOffset == 0 && (SegNum(aPosition) > (PRUint32) mLastSegmentNum))
mWriteCursor = mSegmentEnd;
else
mWriteCursor += segmentOffset;
LOG(("nsStorageStream [%p] Seek mWriteCursor=%x mSegmentEnd=%x\n",
this, mWriteCursor, mSegmentEnd));
return NS_OK;
}
////////////////////////////////////////////////////////////////////////////////
// There can be many nsStorageInputStreams for a single nsStorageStream
class nsStorageInputStream : public nsIInputStream
, public nsISeekableStream
{
public:
nsStorageInputStream(nsStorageStream *aStorageStream, PRUint32 aSegmentSize)
: mStorageStream(aStorageStream), mReadCursor(0),
mSegmentEnd(0), mSegmentNum(0),
mSegmentSize(aSegmentSize), mLogicalCursor(0),
mStatus(NS_OK)
{
NS_ADDREF(mStorageStream);
}
NS_DECL_ISUPPORTS
NS_DECL_NSIINPUTSTREAM
NS_DECL_NSISEEKABLESTREAM
private:
~nsStorageInputStream()
{
NS_IF_RELEASE(mStorageStream);
}
protected:
NS_METHOD Seek(PRUint32 aPosition);
friend class nsStorageStream;
private:
nsStorageStream* mStorageStream;
const char* mReadCursor; // Next memory location to read byte, or NULL
const char* mSegmentEnd; // One byte past end of current buffer segment
PRUint32 mSegmentNum; // Segment number containing read cursor
PRUint32 mSegmentSize; // All segments, except the last, are of this size
PRUint32 mLogicalCursor; // Logical offset into stream
nsresult mStatus;
PRUint32 SegNum(PRUint32 aPosition) {return aPosition >> mStorageStream->mSegmentSizeLog2;}
PRUint32 SegOffset(PRUint32 aPosition) {return aPosition & (mSegmentSize - 1);}
};
NS_IMPL_THREADSAFE_ISUPPORTS2(nsStorageInputStream,
nsIInputStream,
nsISeekableStream)
NS_IMETHODIMP
nsStorageStream::NewInputStream(PRInt32 aStartingOffset, nsIInputStream* *aInputStream)
{
NS_ENSURE_TRUE(mSegmentedBuffer, NS_ERROR_NOT_INITIALIZED);
nsStorageInputStream *inputStream = new nsStorageInputStream(this, mSegmentSize);
if (!inputStream)
return NS_ERROR_OUT_OF_MEMORY;
NS_ADDREF(inputStream);
nsresult rv = inputStream->Seek(aStartingOffset);
if (NS_FAILED(rv)) {
NS_RELEASE(inputStream);
return rv;
}
*aInputStream = inputStream;
return NS_OK;
}
NS_IMETHODIMP
nsStorageInputStream::Close()
{
mStatus = NS_BASE_STREAM_CLOSED;
return NS_OK;
}
NS_IMETHODIMP
nsStorageInputStream::Available(PRUint32 *aAvailable)
{
if (NS_FAILED(mStatus))
return mStatus;
*aAvailable = mStorageStream->mLogicalLength - mLogicalCursor;
return NS_OK;
}
NS_IMETHODIMP
nsStorageInputStream::Read(char* aBuffer, PRUint32 aCount, PRUint32 *aNumRead)
{
return ReadSegments(NS_CopySegmentToBuffer, aBuffer, aCount, aNumRead);
}
NS_IMETHODIMP
nsStorageInputStream::ReadSegments(nsWriteSegmentFun writer, void * closure, PRUint32 aCount, PRUint32 *aNumRead)
{
*aNumRead = 0;
if (mStatus == NS_BASE_STREAM_CLOSED)
return NS_OK;
if (NS_FAILED(mStatus))
return mStatus;
PRUint32 count, availableInSegment, remainingCapacity, bytesConsumed;
nsresult rv;
remainingCapacity = aCount;
while (remainingCapacity) {
availableInSegment = mSegmentEnd - mReadCursor;
if (!availableInSegment) {
PRUint32 available = mStorageStream->mLogicalLength - mLogicalCursor;
if (!available)
goto out;
mReadCursor = mStorageStream->mSegmentedBuffer->GetSegment(++mSegmentNum);
mSegmentEnd = mReadCursor + NS_MIN(mSegmentSize, available);
availableInSegment = mSegmentEnd - mReadCursor;
}
count = NS_MIN(availableInSegment, remainingCapacity);
rv = writer(this, closure, mReadCursor, aCount - remainingCapacity,
count, &bytesConsumed);
if (NS_FAILED(rv) || (bytesConsumed == 0))
break;
remainingCapacity -= bytesConsumed;
mReadCursor += bytesConsumed;
mLogicalCursor += bytesConsumed;
};
out:
*aNumRead = aCount - remainingCapacity;
PRBool isWriteInProgress = PR_FALSE;
if (NS_FAILED(mStorageStream->GetWriteInProgress(&isWriteInProgress)))
isWriteInProgress = PR_FALSE;
if (*aNumRead == 0 && isWriteInProgress)
return NS_BASE_STREAM_WOULD_BLOCK;
return NS_OK;
}
NS_IMETHODIMP
nsStorageInputStream::IsNonBlocking(PRBool *aNonBlocking)
{
// TODO: This class should implement nsIAsyncInputStream so that callers
// have some way of dealing with NS_BASE_STREAM_WOULD_BLOCK errors.
*aNonBlocking = PR_TRUE;
return NS_OK;
}
NS_IMETHODIMP
nsStorageInputStream::Seek(PRInt32 aWhence, PRInt64 aOffset)
{
if (NS_FAILED(mStatus))
return mStatus;
PRInt64 pos = aOffset;
switch (aWhence) {
case NS_SEEK_SET:
break;
case NS_SEEK_CUR:
pos += mLogicalCursor;
break;
case NS_SEEK_END:
pos += mStorageStream->mLogicalLength;
break;
default:
NS_NOTREACHED("unexpected whence value");
return NS_ERROR_UNEXPECTED;
}
if (pos == PRInt64(mLogicalCursor))
return NS_OK;
return Seek(pos);
}
NS_IMETHODIMP
nsStorageInputStream::Tell(PRInt64 *aResult)
{
if (NS_FAILED(mStatus))
return mStatus;
LL_UI2L(*aResult, mLogicalCursor);
return NS_OK;
}
NS_IMETHODIMP
nsStorageInputStream::SetEOF()
{
NS_NOTREACHED("nsStorageInputStream::SetEOF");
return NS_ERROR_NOT_IMPLEMENTED;
}
NS_METHOD
nsStorageInputStream::Seek(PRUint32 aPosition)
{
PRUint32 length = mStorageStream->mLogicalLength;
if (aPosition > length)
return NS_ERROR_INVALID_ARG;
if (length == 0)
return NS_OK;
mSegmentNum = SegNum(aPosition);
PRUint32 segmentOffset = SegOffset(aPosition);
mReadCursor = mStorageStream->mSegmentedBuffer->GetSegment(mSegmentNum) +
segmentOffset;
PRUint32 available = length - aPosition;
mSegmentEnd = mReadCursor + NS_MIN(mSegmentSize - segmentOffset, available);
mLogicalCursor = aPosition;
return NS_OK;
}
NS_COM nsresult
NS_NewStorageStream(PRUint32 segmentSize, PRUint32 maxSize, nsIStorageStream **result)
{
NS_ENSURE_ARG(result);
nsStorageStream* storageStream = new nsStorageStream();
if (!storageStream) return NS_ERROR_OUT_OF_MEMORY;
NS_ADDREF(storageStream);
nsresult rv = storageStream->Init(segmentSize, maxSize, nsnull);
if (NS_FAILED(rv)) {
NS_RELEASE(storageStream);
return rv;
}
*result = storageStream;
return NS_OK;
}