gecko-dev/netwerk/base/SimpleBuffer.cpp

96 строки
2.4 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "SimpleBuffer.h"
#include <algorithm>
namespace mozilla {
namespace net {
SimpleBuffer::SimpleBuffer()
: mStatus(NS_OK)
, mAvailable(0)
{
mOwningThread = PR_GetCurrentThread();
}
nsresult SimpleBuffer::Write(char *src, size_t len)
{
MOZ_ASSERT(PR_GetCurrentThread() == mOwningThread);
if (NS_FAILED(mStatus)) {
return mStatus;
}
while (len > 0) {
SimpleBufferPage *p = mBufferList.getLast();
if (p && (p->mWriteOffset == SimpleBufferPage::kSimpleBufferPageSize)) {
// no room.. make a new page
p = nullptr;
}
if (!p) {
p = new (fallible) SimpleBufferPage();
if (!p) {
mStatus = NS_ERROR_OUT_OF_MEMORY;
return mStatus;
}
mBufferList.insertBack(p);
}
size_t roomOnPage = SimpleBufferPage::kSimpleBufferPageSize - p->mWriteOffset;
size_t toWrite = std::min(roomOnPage, len);
memcpy(p->mBuffer + p->mWriteOffset, src, toWrite);
src += toWrite;
len -= toWrite;
p->mWriteOffset += toWrite;
mAvailable += toWrite;
}
return NS_OK;
}
size_t SimpleBuffer::Read(char *dest, size_t maxLen)
{
MOZ_ASSERT(PR_GetCurrentThread() == mOwningThread);
if (NS_FAILED(mStatus)) {
return 0;
}
size_t rv = 0;
for (SimpleBufferPage *p = mBufferList.getFirst();
p && (rv < maxLen); p = mBufferList.getFirst()) {
size_t avail = p->mWriteOffset - p->mReadOffset;
size_t toRead = std::min(avail, (maxLen - rv));
memcpy(dest + rv, p->mBuffer + p->mReadOffset, toRead);
rv += toRead;
p->mReadOffset += toRead;
if (p->mReadOffset == p->mWriteOffset) {
p->remove();
delete p;
}
}
MOZ_ASSERT(mAvailable >= rv);
mAvailable -= rv;
return rv;
}
size_t SimpleBuffer::Available()
{
MOZ_ASSERT(PR_GetCurrentThread() == mOwningThread);
return NS_SUCCEEDED(mStatus) ? mAvailable : 0;
}
void SimpleBuffer::Clear()
{
MOZ_ASSERT(PR_GetCurrentThread() == mOwningThread);
SimpleBufferPage *p;
while ((p = mBufferList.popFirst())) {
delete p;
}
mAvailable = 0;
}
} // namespace net
} // namespace mozilla