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nsPipe3.cpp
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 <algorithm>
#include "mozilla/Attributes.h"
#include "mozilla/ReentrantMonitor.h"
#include "nsICloneableInputStream.h"
#include "nsIPipe.h"
#include "nsIEventTarget.h"
#include "nsISeekableStream.h"
#include "mozilla/RefPtr.h"
#include "nsSegmentedBuffer.h"
#include "nsStreamUtils.h"
#include "nsCOMPtr.h"
#include "nsCRT.h"
#include "mozilla/Logging.h"
#include "nsIClassInfoImpl.h"
#include "nsAlgorithm.h"
#include "nsMemory.h"
#include "nsIAsyncInputStream.h"
#include "nsIAsyncOutputStream.h"
using namespace mozilla;
#ifdef LOG
#undef LOG
#endif
//
// set NSPR_LOG_MODULES=nsPipe:5
//
static LazyLogModule sPipeLog("nsPipe");
#define LOG(args) MOZ_LOG(sPipeLog, mozilla::LogLevel::Debug, args)
#define DEFAULT_SEGMENT_SIZE 4096
#define DEFAULT_SEGMENT_COUNT 16
class nsPipe;
class nsPipeEvents;
class nsPipeInputStream;
class nsPipeOutputStream;
class AutoReadSegment;
namespace {
enum MonitorAction
{
DoNotNotifyMonitor,
NotifyMonitor
};
enum SegmentChangeResult
{
SegmentNotChanged,
SegmentDeleted
};
} // namespace
//-----------------------------------------------------------------------------
// this class is used to delay notifications until the end of a particular
// scope. it helps avoid the complexity of issuing callbacks while inside
// a critical section.
class nsPipeEvents
{
public:
nsPipeEvents() { }
~nsPipeEvents();
inline void NotifyInputReady(nsIAsyncInputStream* aStream,
nsIInputStreamCallback* aCallback)
{
mInputList.AppendElement(InputEntry(aStream, aCallback));
}
inline void NotifyOutputReady(nsIAsyncOutputStream* aStream,
nsIOutputStreamCallback* aCallback)
{
NS_ASSERTION(!mOutputCallback, "already have an output event");
mOutputStream = aStream;
mOutputCallback = aCallback;
}
private:
struct InputEntry
{
InputEntry(nsIAsyncInputStream* aStream, nsIInputStreamCallback* aCallback)
: mStream(aStream)
, mCallback(aCallback)
{
MOZ_ASSERT(mStream);
MOZ_ASSERT(mCallback);
}
nsCOMPtr<nsIAsyncInputStream> mStream;
nsCOMPtr<nsIInputStreamCallback> mCallback;
};
nsTArray<InputEntry> mInputList;
nsCOMPtr<nsIAsyncOutputStream> mOutputStream;
nsCOMPtr<nsIOutputStreamCallback> mOutputCallback;
};
//-----------------------------------------------------------------------------
// This class is used to maintain input stream state. Its broken out from the
// nsPipeInputStream class because generally the nsPipe should be modifying
// this state and not the input stream itself.
struct nsPipeReadState
{
nsPipeReadState()
: mReadCursor(nullptr)
, mReadLimit(nullptr)
, mSegment(0)
, mAvailable(0)
, mActiveRead(false)
, mNeedDrain(false)
{ }
char* mReadCursor;
char* mReadLimit;
int32_t mSegment;
uint32_t mAvailable;
// This flag is managed using the AutoReadSegment RAII stack class.
bool mActiveRead;
// Set to indicate that the input stream has closed and should be drained,
// but that drain has been delayed due to an active read. When the read
// completes, this flag indicate the drain should then be performed.
bool mNeedDrain;
};
//-----------------------------------------------------------------------------
// an input end of a pipe (maintained as a list of refs within the pipe)
class nsPipeInputStream final
: public nsIAsyncInputStream
, public nsISeekableStream
, public nsISearchableInputStream
, public nsICloneableInputStream
, public nsIClassInfo
{
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIINPUTSTREAM
NS_DECL_NSIASYNCINPUTSTREAM
NS_DECL_NSISEEKABLESTREAM
NS_DECL_NSISEARCHABLEINPUTSTREAM
NS_DECL_NSICLONEABLEINPUTSTREAM
NS_DECL_NSICLASSINFO
explicit nsPipeInputStream(nsPipe* aPipe)
: mPipe(aPipe)
, mLogicalOffset(0)
, mInputStatus(NS_OK)
, mBlocking(true)
, mBlocked(false)
, mCallbackFlags(0)
{ }
explicit nsPipeInputStream(const nsPipeInputStream& aOther)
: mPipe(aOther.mPipe)
, mLogicalOffset(aOther.mLogicalOffset)
, mInputStatus(aOther.mInputStatus)
, mBlocking(aOther.mBlocking)
, mBlocked(false)
, mCallbackFlags(0)
, mReadState(aOther.mReadState)
{ }
nsresult Fill();
void SetNonBlocking(bool aNonBlocking)
{
mBlocking = !aNonBlocking;
}
uint32_t Available();
// synchronously wait for the pipe to become readable.
nsresult Wait();
// These two don't acquire the monitor themselves. Instead they
// expect their caller to have done so and to pass the monitor as
// evidence.
MonitorAction OnInputReadable(uint32_t aBytesWritten, nsPipeEvents&,
const ReentrantMonitorAutoEnter& ev);
MonitorAction OnInputException(nsresult, nsPipeEvents&,
const ReentrantMonitorAutoEnter& ev);
nsPipeReadState& ReadState()
{
return mReadState;
}
const nsPipeReadState& ReadState() const
{
return mReadState;
}
nsresult Status() const;
// A version of Status() that doesn't acquire the monitor.
nsresult Status(const ReentrantMonitorAutoEnter& ev) const;
private:
virtual ~nsPipeInputStream();
RefPtr<nsPipe> mPipe;
int64_t mLogicalOffset;
// Individual input streams can be closed without effecting the rest of the
// pipe. So track individual input stream status separately. |mInputStatus|
// is protected by |mPipe->mReentrantMonitor|.
nsresult mInputStatus;
bool mBlocking;
// these variables can only be accessed while inside the pipe's monitor
bool mBlocked;
nsCOMPtr<nsIInputStreamCallback> mCallback;
uint32_t mCallbackFlags;
// requires pipe's monitor; usually treat as an opaque token to pass to nsPipe
nsPipeReadState mReadState;
};
//-----------------------------------------------------------------------------
// the output end of a pipe (allocated as a member of the pipe).
class nsPipeOutputStream
: public nsIAsyncOutputStream
, public nsIClassInfo
{
public:
// since this class will be allocated as a member of the pipe, we do not
// need our own ref count. instead, we share the lifetime (the ref count)
// of the entire pipe. this macro is just convenience since it does not
// declare a mRefCount variable; however, don't let the name fool you...
// we are not inheriting from nsPipe ;-)
NS_DECL_ISUPPORTS_INHERITED
NS_DECL_NSIOUTPUTSTREAM
NS_DECL_NSIASYNCOUTPUTSTREAM
NS_DECL_NSICLASSINFO
explicit nsPipeOutputStream(nsPipe* aPipe)
: mPipe(aPipe)
, mWriterRefCnt(0)
, mLogicalOffset(0)
, mBlocking(true)
, mBlocked(false)
, mWritable(true)
, mCallbackFlags(0)
{ }
void SetNonBlocking(bool aNonBlocking)
{
mBlocking = !aNonBlocking;
}
void SetWritable(bool aWritable)
{
mWritable = aWritable;
}
// synchronously wait for the pipe to become writable.
nsresult Wait();
MonitorAction OnOutputWritable(nsPipeEvents&);
MonitorAction OnOutputException(nsresult, nsPipeEvents&);
private:
nsPipe* mPipe;
// separate refcnt so that we know when to close the producer
mozilla::ThreadSafeAutoRefCnt mWriterRefCnt;
int64_t mLogicalOffset;
bool mBlocking;
// these variables can only be accessed while inside the pipe's monitor
bool mBlocked;
bool mWritable;
nsCOMPtr<nsIOutputStreamCallback> mCallback;
uint32_t mCallbackFlags;
};
//-----------------------------------------------------------------------------
class nsPipe final : public nsIPipe
{
public:
friend class nsPipeInputStream;
friend class nsPipeOutputStream;
friend class AutoReadSegment;
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIPIPE
// nsPipe methods:
nsPipe();
private:
~nsPipe();
//
// methods below may only be called while inside the pipe's monitor
//
void PeekSegment(const nsPipeReadState& aReadState, uint32_t aIndex,
char*& aCursor, char*& aLimit);
SegmentChangeResult AdvanceReadSegment(nsPipeReadState& aReadState);
bool ReadSegmentBeingWritten(nsPipeReadState& aReadState);
uint32_t CountSegmentReferences(int32_t aSegment);
void SetAllNullReadCursors();
bool AllReadCursorsMatchWriteCursor();
void RollBackAllReadCursors(char* aWriteCursor);
void UpdateAllReadCursors(char* aWriteCursor);
void ValidateAllReadCursors();
//
// methods below may be called while outside the pipe's monitor
//
void DrainInputStream(nsPipeReadState& aReadState, nsPipeEvents& aEvents);
nsresult GetWriteSegment(char*& aSegment, uint32_t& aSegmentLen);
void AdvanceWriteCursor(uint32_t aCount);
void OnInputStreamException(nsPipeInputStream* aStream, nsresult aReason);
void OnPipeException(nsresult aReason, bool aOutputOnly = false);
nsresult CloneInputStream(nsPipeInputStream* aOriginal,
nsIInputStream** aCloneOut);
// methods below should only be called by AutoReadSegment
nsresult GetReadSegment(nsPipeReadState& aReadState, const char*& aSegment,
uint32_t& aLength);
void ReleaseReadSegment(nsPipeReadState& aReadState,
nsPipeEvents& aEvents);
void AdvanceReadCursor(nsPipeReadState& aReadState, uint32_t aCount);
// We can't inherit from both nsIInputStream and nsIOutputStream
// because they collide on their Close method. Consequently we nest their
// implementations to avoid the extra object allocation.
nsPipeOutputStream mOutput;
// Since the input stream can be cloned, we may have more than one. Use
// a weak reference as the streams will clear their entry here in their
// destructor. Using a strong reference would create a reference cycle.
// Only usable while mReentrantMonitor is locked.
nsTArray<nsPipeInputStream*> mInputList;
// But hold a strong ref to our original input stream. For backward
// compatibility we need to be able to consistently return this same
// object from GetInputStream(). Note, mOriginalInput is also stored
// in mInputList as a weak ref.
RefPtr<nsPipeInputStream> mOriginalInput;
ReentrantMonitor mReentrantMonitor;
nsSegmentedBuffer mBuffer;
int32_t mWriteSegment;
char* mWriteCursor;
char* mWriteLimit;
// |mStatus| is protected by |mReentrantMonitor|.
nsresult mStatus;
bool mInited;
};
//-----------------------------------------------------------------------------
// RAII class representing an active read segment. When it goes out of scope
// it automatically updates the read cursor and releases the read segment.
class MOZ_STACK_CLASS AutoReadSegment final
{
public:
AutoReadSegment(nsPipe* aPipe, nsPipeReadState& aReadState,
uint32_t aMaxLength)
: mPipe(aPipe)
, mReadState(aReadState)
, mStatus(NS_ERROR_FAILURE)
, mSegment(nullptr)
, mLength(0)
, mOffset(0)
{
MOZ_ASSERT(mPipe);
MOZ_ASSERT(!mReadState.mActiveRead);
mStatus = mPipe->GetReadSegment(mReadState, mSegment, mLength);
if (NS_SUCCEEDED(mStatus)) {
MOZ_ASSERT(mReadState.mActiveRead);
MOZ_ASSERT(mSegment);
mLength = std::min(mLength, aMaxLength);
MOZ_ASSERT(mLength);
}
}
~AutoReadSegment()
{
if (NS_SUCCEEDED(mStatus)) {
if (mOffset) {
mPipe->AdvanceReadCursor(mReadState, mOffset);
} else {
nsPipeEvents events;
mPipe->ReleaseReadSegment(mReadState, events);
}
}
MOZ_ASSERT(!mReadState.mActiveRead);
}
nsresult Status() const
{
return mStatus;
}
const char* Data() const
{
MOZ_ASSERT(NS_SUCCEEDED(mStatus));
MOZ_ASSERT(mSegment);
return mSegment + mOffset;
}
uint32_t Length() const
{
MOZ_ASSERT(NS_SUCCEEDED(mStatus));
MOZ_ASSERT(mLength >= mOffset);
return mLength - mOffset;
}
void
Advance(uint32_t aCount)
{
MOZ_ASSERT(NS_SUCCEEDED(mStatus));
MOZ_ASSERT(aCount <= (mLength - mOffset));
mOffset += aCount;
}
nsPipeReadState&
ReadState() const
{
return mReadState;
}
private:
// guaranteed to remain alive due to limited stack lifetime of AutoReadSegment
nsPipe* mPipe;
nsPipeReadState& mReadState;
nsresult mStatus;
const char* mSegment;
uint32_t mLength;
uint32_t mOffset;
};
//
// NOTES on buffer architecture:
//
// +-----------------+ - - mBuffer.GetSegment(0)
// | |
// + - - - - - - - - + - - nsPipeReadState.mReadCursor
// |/////////////////|
// |/////////////////|
// |/////////////////|
// |/////////////////|
// +-----------------+ - - nsPipeReadState.mReadLimit
// |
// +-----------------+
// |/////////////////|
// |/////////////////|
// |/////////////////|
// |/////////////////|
// |/////////////////|
// |/////////////////|
// +-----------------+
// |
// +-----------------+ - - mBuffer.GetSegment(mWriteSegment)
// |/////////////////|
// |/////////////////|
// |/////////////////|
// + - - - - - - - - + - - mWriteCursor
// | |
// | |
// +-----------------+ - - mWriteLimit
//
// (shaded region contains data)
//
// NOTE: Each input stream produced by the nsPipe contains its own, separate
// nsPipeReadState. This means there are multiple mReadCursor and
// mReadLimit values in play. The pipe cannot discard old data until
// all mReadCursors have moved beyond that point in the stream.
//
// NOTE: on some systems (notably OS/2), the heap allocator uses an arena for
// small allocations (e.g., 64 byte allocations). this means that buffers may
// be allocated back-to-back. in the diagram above, for example, mReadLimit
// would actually be pointing at the beginning of the next segment. when
// making changes to this file, please keep this fact in mind.
//
//-----------------------------------------------------------------------------
// nsPipe methods:
//-----------------------------------------------------------------------------
nsPipe::nsPipe()
: mOutput(this)
, mOriginalInput(new nsPipeInputStream(this))
, mReentrantMonitor("nsPipe.mReentrantMonitor")
, mWriteSegment(-1)
, mWriteCursor(nullptr)
, mWriteLimit(nullptr)
, mStatus(NS_OK)
, mInited(false)
{
mInputList.AppendElement(mOriginalInput);
}
nsPipe::~nsPipe()
{
}
NS_IMPL_ADDREF(nsPipe)
NS_IMPL_QUERY_INTERFACE(nsPipe, nsIPipe)
NS_IMETHODIMP_(MozExternalRefCountType)
nsPipe::Release()
{
MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");
nsrefcnt count = --mRefCnt;
NS_LOG_RELEASE(this, count, "nsPipe");
if (count == 0) {
delete (this);
return 0;
}
// Avoid racing on |mOriginalInput| by only looking at it when
// the refcount is 1, that is, we are the only pointer (hence only
// thread) to access it.
if (count == 1 && mOriginalInput) {
mOriginalInput = nullptr;
return 1;
}
return count;
}
NS_IMETHODIMP
nsPipe::Init(bool aNonBlockingIn,
bool aNonBlockingOut,
uint32_t aSegmentSize,
uint32_t aSegmentCount)
{
mInited = true;
if (aSegmentSize == 0) {
aSegmentSize = DEFAULT_SEGMENT_SIZE;
}
if (aSegmentCount == 0) {
aSegmentCount = DEFAULT_SEGMENT_COUNT;
}
// protect against overflow
uint32_t maxCount = uint32_t(-1) / aSegmentSize;
if (aSegmentCount > maxCount) {
aSegmentCount = maxCount;
}
nsresult rv = mBuffer.Init(aSegmentSize, aSegmentSize * aSegmentCount);
if (NS_FAILED(rv)) {
return rv;
}
mOutput.SetNonBlocking(aNonBlockingOut);
mOriginalInput->SetNonBlocking(aNonBlockingIn);
return NS_OK;
}
NS_IMETHODIMP
nsPipe::GetInputStream(nsIAsyncInputStream** aInputStream)
{
RefPtr<nsPipeInputStream> ref = mOriginalInput;
ref.forget(aInputStream);
return NS_OK;
}
NS_IMETHODIMP
nsPipe::GetOutputStream(nsIAsyncOutputStream** aOutputStream)
{
if (NS_WARN_IF(!mInited)) {
return NS_ERROR_NOT_INITIALIZED;
}
NS_ADDREF(*aOutputStream = &mOutput);
return NS_OK;
}
void
nsPipe::PeekSegment(const nsPipeReadState& aReadState, uint32_t aIndex,
char*& aCursor, char*& aLimit)
{
if (aIndex == 0) {
NS_ASSERTION(!aReadState.mReadCursor || mBuffer.GetSegmentCount(),
"unexpected state");
aCursor = aReadState.mReadCursor;
aLimit = aReadState.mReadLimit;
} else {
uint32_t absoluteIndex = aReadState.mSegment + aIndex;
uint32_t numSegments = mBuffer.GetSegmentCount();
if (absoluteIndex >= numSegments) {
aCursor = aLimit = nullptr;
} else {
aCursor = mBuffer.GetSegment(absoluteIndex);
if (mWriteSegment == (int32_t)absoluteIndex) {
aLimit = mWriteCursor;
} else {
aLimit = aCursor + mBuffer.GetSegmentSize();
}
}
}
}
nsresult
nsPipe::GetReadSegment(nsPipeReadState& aReadState, const char*& aSegment,
uint32_t& aLength)
{
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
if (aReadState.mReadCursor == aReadState.mReadLimit) {
return NS_FAILED(mStatus) ? mStatus : NS_BASE_STREAM_WOULD_BLOCK;
}
// The input stream locks the pipe while getting the buffer to read from,
// but then unlocks while actual data copying is taking place. In
// order to avoid deleting the buffer out from under this lockless read
// set a flag to indicate a read is active. This flag is only modified
// while the lock is held.
MOZ_ASSERT(!aReadState.mActiveRead);
aReadState.mActiveRead = true;
aSegment = aReadState.mReadCursor;
aLength = aReadState.mReadLimit - aReadState.mReadCursor;
return NS_OK;
}
void
nsPipe::ReleaseReadSegment(nsPipeReadState& aReadState, nsPipeEvents& aEvents)
{
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
MOZ_ASSERT(aReadState.mActiveRead);
aReadState.mActiveRead = false;
// When a read completes and releases the mActiveRead flag, we may have blocked
// a drain from completing. This occurs when the input stream is closed during
// the read. In these cases, we need to complete the drain as soon as the
// active read completes.
if (aReadState.mNeedDrain) {
aReadState.mNeedDrain = false;
DrainInputStream(aReadState, aEvents);
}
}
void
nsPipe::AdvanceReadCursor(nsPipeReadState& aReadState, uint32_t aBytesRead)
{
NS_ASSERTION(aBytesRead, "don't call if no bytes read");
nsPipeEvents events;
{
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
LOG(("III advancing read cursor by %u\n", aBytesRead));
NS_ASSERTION(aBytesRead <= mBuffer.GetSegmentSize(), "read too much");
aReadState.mReadCursor += aBytesRead;
NS_ASSERTION(aReadState.mReadCursor <= aReadState.mReadLimit,
"read cursor exceeds limit");
MOZ_ASSERT(aReadState.mAvailable >= aBytesRead);
aReadState.mAvailable -= aBytesRead;
// Check to see if we're at the end of the available read data. If we
// are, and this segment is not still being written, then we can possibly
// free up the segment.
if (aReadState.mReadCursor == aReadState.mReadLimit &&
!ReadSegmentBeingWritten(aReadState)) {
// Check to see if we can free up any segments. If we can, then notify
// the output stream that the pipe has room for a new segment.
if (AdvanceReadSegment(aReadState) == SegmentDeleted &&
mOutput.OnOutputWritable(events) == NotifyMonitor) {
mon.NotifyAll();
}
}
ReleaseReadSegment(aReadState, events);
}
}
SegmentChangeResult
nsPipe::AdvanceReadSegment(nsPipeReadState& aReadState)
{
mReentrantMonitor.AssertCurrentThreadIn();
int32_t currentSegment = aReadState.mSegment;
// Move to the next segment to read
aReadState.mSegment += 1;
SegmentChangeResult result = SegmentNotChanged;
// If this was the last reference to the first segment, then remove it.
if (currentSegment == 0 && CountSegmentReferences(currentSegment) == 0) {
// shift write and read segment index (-1 indicates an empty buffer).
mWriteSegment -= 1;
// Directly modify the current read state. If the associated input
// stream is closed simultaneous with reading, then it may not be
// in the mInputList any more.
aReadState.mSegment -= 1;
for (uint32_t i = 0; i < mInputList.Length(); ++i) {
// Skip the current read state structure since we modify it manually
// before entering this loop.
if (&mInputList[i]->ReadState() == &aReadState) {
continue;
}
mInputList[i]->ReadState().mSegment -= 1;
}
// done with this segment
mBuffer.DeleteFirstSegment();
LOG(("III deleting first segment\n"));
result = SegmentDeleted;
}
if (mWriteSegment < aReadState.mSegment) {
// read cursor has hit the end of written data, so reset it
MOZ_ASSERT(mWriteSegment == (aReadState.mSegment - 1));
aReadState.mReadCursor = nullptr;
aReadState.mReadLimit = nullptr;
// also, the buffer is completely empty, so reset the write cursor
if (mWriteSegment == -1) {
mWriteCursor = nullptr;
mWriteLimit = nullptr;
}
} else {
// advance read cursor and limit to next buffer segment
aReadState.mReadCursor = mBuffer.GetSegment(aReadState.mSegment);
if (mWriteSegment == aReadState.mSegment) {
aReadState.mReadLimit = mWriteCursor;
} else {
aReadState.mReadLimit = aReadState.mReadCursor + mBuffer.GetSegmentSize();
}
}
return result;
}
void
nsPipe::DrainInputStream(nsPipeReadState& aReadState, nsPipeEvents& aEvents)
{
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
// If a segment is actively being read in ReadSegments() for this input
// stream, then we cannot drain the stream. This can happen because
// ReadSegments() does not hold the lock while copying from the buffer.
// If we detect this condition, simply note that we need a drain once
// the read completes and return immediately.
if (aReadState.mActiveRead) {
MOZ_ASSERT(!aReadState.mNeedDrain);
aReadState.mNeedDrain = true;
return;
}
aReadState.mAvailable = 0;
SegmentChangeResult result = SegmentNotChanged;
while(mWriteSegment >= aReadState.mSegment) {
// If the last segment to free is still being written to, we're done
// draining. We can't free any more.
if (ReadSegmentBeingWritten(aReadState)) {
break;
}
if (AdvanceReadSegment(aReadState) == SegmentDeleted) {
result = SegmentDeleted;
}
}
// if we've free'd up a segment, notify output stream that pipe has
// room for a new segment.
if (result == SegmentDeleted &&
mOutput.OnOutputWritable(aEvents) == NotifyMonitor) {
mon.NotifyAll();
}
}
bool
nsPipe::ReadSegmentBeingWritten(nsPipeReadState& aReadState)
{
mReentrantMonitor.AssertCurrentThreadIn();
bool beingWritten = mWriteSegment == aReadState.mSegment &&
mWriteLimit > mWriteCursor;
NS_ASSERTION(!beingWritten || aReadState.mReadLimit == mWriteCursor,
"unexpected state");
return beingWritten;
}
nsresult
nsPipe::GetWriteSegment(char*& aSegment, uint32_t& aSegmentLen)
{
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
if (NS_FAILED(mStatus)) {
return mStatus;
}
// write cursor and limit may both be null indicating an empty buffer.
if (mWriteCursor == mWriteLimit) {
char* seg = mBuffer.AppendNewSegment();
// pipe is full
if (!seg) {
return NS_BASE_STREAM_WOULD_BLOCK;
}
LOG(("OOO appended new segment\n"));
mWriteCursor = seg;
mWriteLimit = mWriteCursor + mBuffer.GetSegmentSize();
++mWriteSegment;
}
// make sure read cursor is initialized
SetAllNullReadCursors();
// check to see if we can roll-back our read and write cursors to the
// beginning of the current/first segment. this is purely an optimization.
if (mWriteSegment == 0 && AllReadCursorsMatchWriteCursor()) {
char* head = mBuffer.GetSegment(0);
LOG(("OOO rolling back write cursor %u bytes\n", mWriteCursor - head));
RollBackAllReadCursors(head);
mWriteCursor = head;
}
aSegment = mWriteCursor;
aSegmentLen = mWriteLimit - mWriteCursor;
return NS_OK;
}
void
nsPipe::AdvanceWriteCursor(uint32_t aBytesWritten)
{
NS_ASSERTION(aBytesWritten, "don't call if no bytes written");
nsPipeEvents events;
{
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
LOG(("OOO advancing write cursor by %u\n", aBytesWritten));
char* newWriteCursor = mWriteCursor + aBytesWritten;
NS_ASSERTION(newWriteCursor <= mWriteLimit, "write cursor exceeds limit");
// update read limit if reading in the same segment
UpdateAllReadCursors(newWriteCursor);
mWriteCursor = newWriteCursor;
ValidateAllReadCursors();
// update the writable flag on the output stream
if (mWriteCursor == mWriteLimit) {
if (mBuffer.GetSize() >= mBuffer.GetMaxSize()) {
mOutput.SetWritable(false);
}
}
// notify input stream that pipe now contains additional data
bool needNotify = false;
for (uint32_t i = 0; i < mInputList.Length(); ++i) {
if (mInputList[i]->OnInputReadable(aBytesWritten, events, mon)
== NotifyMonitor) {
needNotify = true;
}
}
if (needNotify) {
mon.NotifyAll();
}
}
}
void
nsPipe::OnInputStreamException(nsPipeInputStream* aStream, nsresult aReason)
{
MOZ_ASSERT(NS_FAILED(aReason));
nsPipeEvents events;
{
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
// Its possible to re-enter this method when we call OnPipeException() or
// OnInputExection() below. If there is a caller stuck in our synchronous
// Wait() method, then they will get woken up with a failure code which
// re-enters this method. Therefore, gracefully handle unknown streams
// here.
// If we only have one stream open and it is the given stream, then shut
// down the entire pipe.
if (mInputList.Length() == 1) {
if (mInputList[0] == aStream) {
OnPipeException(aReason);
}
return;
}
// Otherwise just close the particular stream that hit an exception.
for (uint32_t i = 0; i < mInputList.Length(); ++i) {
if (mInputList[i] != aStream) {
continue;
}
MonitorAction action = mInputList[i]->OnInputException(aReason, events,
mon);
mInputList.RemoveElementAt(i);
// Notify after element is removed in case we re-enter as a result.
if (action == NotifyMonitor) {
mon.NotifyAll();
}
return;
}
}
}
void
nsPipe::OnPipeException(nsresult aReason, bool aOutputOnly)
{
LOG(("PPP nsPipe::OnPipeException [reason=%x output-only=%d]\n",
aReason, aOutputOnly));
nsPipeEvents events;
{
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
// if we've already hit an exception, then ignore this one.
if (NS_FAILED(mStatus)) {
return;
}
mStatus = aReason;
bool needNotify = false;
nsTArray<nsPipeInputStream*> tmpInputList;
for (uint32_t i = 0; i < mInputList.Length(); ++i) {
// an output-only exception applies to the input end if the pipe has
// zero bytes available.
if (aOutputOnly && mInputList[i]->Available()) {
tmpInputList.AppendElement(mInputList[i]);
continue;
}
if (mInputList[i]->OnInputException(aReason, events, mon)
== NotifyMonitor) {
needNotify = true;
}
}
mInputList = tmpInputList;
if (mOutput.OnOutputException(aReason, events) == NotifyMonitor) {
needNotify = true;
}
// Notify after we have removed any input streams from mInputList
if (needNotify) {
mon.NotifyAll();
}
}
}
nsresult
nsPipe::CloneInputStream(nsPipeInputStream* aOriginal,
nsIInputStream** aCloneOut)
{
ReentrantMonitorAutoEnter mon(mReentrantMonitor);
RefPtr<nsPipeInputStream> ref = new nsPipeInputStream(*aOriginal);
mInputList.AppendElement(ref);
ref.forget(aCloneOut);
return NS_OK;
}
uint32_t
nsPipe::CountSegmentReferences(int32_t aSegment)
{
mReentrantMonitor.AssertCurrentThreadIn();
uint32_t count = 0;
for (uint32_t i = 0; i < mInputList.Length(); ++i) {