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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 "nsSegmentedBuffer.h"
#include "nsMemory.h"
#include "nsNetCID.h"
#include "nsServiceManagerUtils.h"
#include "nsThreadUtils.h"
#include "mozilla/ScopeExit.h"
nsresult nsSegmentedBuffer::Init(uint32_t aSegmentSize, uint32_t aMaxSize) {
if (mSegmentArrayCount != 0) {
return NS_ERROR_FAILURE; // initialized more than once
}
mSegmentSize = aSegmentSize;
mMaxSize = aMaxSize;
#if 0 // testing...
mSegmentArrayCount = 2;
#else
mSegmentArrayCount = NS_SEGMENTARRAY_INITIAL_COUNT;
#endif
return NS_OK;
}
char* nsSegmentedBuffer::AppendNewSegment() {
if (GetSize() >= mMaxSize) {
return nullptr;
}
if (!mSegmentArray) {
uint32_t bytes = mSegmentArrayCount * sizeof(char*);
mSegmentArray = (char**)moz_xmalloc(bytes);
memset(mSegmentArray, 0, bytes);
}
if (IsFull()) {
uint32_t newArraySize = mSegmentArrayCount * 2;
uint32_t bytes = newArraySize * sizeof(char*);
mSegmentArray = (char**)moz_xrealloc(mSegmentArray, bytes);
// copy wrapped content to new extension
if (mFirstSegmentIndex > mLastSegmentIndex) {
// deal with wrap around case
memcpy(&mSegmentArray[mSegmentArrayCount], mSegmentArray,
mLastSegmentIndex * sizeof(char*));
memset(mSegmentArray, 0, mLastSegmentIndex * sizeof(char*));
mLastSegmentIndex += mSegmentArrayCount;
memset(&mSegmentArray[mLastSegmentIndex], 0,
(newArraySize - mLastSegmentIndex) * sizeof(char*));
} else {
memset(&mSegmentArray[mLastSegmentIndex], 0,
(newArraySize - mLastSegmentIndex) * sizeof(char*));
}
mSegmentArrayCount = newArraySize;
}
char* seg = (char*)malloc(mSegmentSize);
if (!seg) {
return nullptr;
}
mSegmentArray[mLastSegmentIndex] = seg;
mLastSegmentIndex = ModSegArraySize(mLastSegmentIndex + 1);
return seg;
}
bool nsSegmentedBuffer::DeleteFirstSegment() {
NS_ASSERTION(mSegmentArray[mFirstSegmentIndex] != nullptr,
"deleting bad segment");
FreeOMT(mSegmentArray[mFirstSegmentIndex]);
mSegmentArray[mFirstSegmentIndex] = nullptr;
int32_t last = ModSegArraySize(mLastSegmentIndex - 1);
if (mFirstSegmentIndex == last) {
mLastSegmentIndex = last;
return true;
} else {
mFirstSegmentIndex = ModSegArraySize(mFirstSegmentIndex + 1);
return false;
}
}
bool nsSegmentedBuffer::DeleteLastSegment() {
int32_t last = ModSegArraySize(mLastSegmentIndex - 1);
NS_ASSERTION(mSegmentArray[last] != nullptr, "deleting bad segment");
FreeOMT(mSegmentArray[last]);
mSegmentArray[last] = nullptr;
mLastSegmentIndex = last;
return (bool)(mLastSegmentIndex == mFirstSegmentIndex);
}
bool nsSegmentedBuffer::ReallocLastSegment(size_t aNewSize) {
int32_t last = ModSegArraySize(mLastSegmentIndex - 1);
NS_ASSERTION(mSegmentArray[last] != nullptr, "realloc'ing bad segment");
char* newSegment = (char*)realloc(mSegmentArray[last], aNewSize);
if (newSegment) {
mSegmentArray[last] = newSegment;
return true;
}
return false;
}
void nsSegmentedBuffer::Empty() {
auto clearMembers = mozilla::MakeScopeExit([&] {
mSegmentArray = nullptr;
mSegmentArrayCount = NS_SEGMENTARRAY_INITIAL_COUNT;
mFirstSegmentIndex = mLastSegmentIndex = 0;
});
// If mSegmentArray is null, there's no need to actually free anything
if (!mSegmentArray) {
return;
}
// Dispatch a task that frees up the array. This may run immediately or on
// a background thread.
FreeOMT([segmentArray = mSegmentArray, arrayCount = mSegmentArrayCount]() {
for (uint32_t i = 0; i < arrayCount; i++) {
if (segmentArray[i]) {
free(segmentArray[i]);
}
}
free(segmentArray);
});
}
void nsSegmentedBuffer::FreeOMT(void* aPtr) {
FreeOMT([aPtr]() { free(aPtr); });
}
void nsSegmentedBuffer::FreeOMT(std::function<void()>&& aTask) {
if (!NS_IsMainThread()) {
aTask();
return;
}
if (mFreeOMT) {
// There is a runnable pending which will handle this object
if (mFreeOMT->AddTask(std::move(aTask)) > 1) {
return;
}
} else {
mFreeOMT = MakeRefPtr<FreeOMTPointers>();
mFreeOMT->AddTask(std::move(aTask));
}
if (!mIOThread) {
mIOThread = do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID);
}
// During the shutdown we are not able to obtain the IOThread and/or the
// dispatching of runnable fails.
if (!mIOThread || NS_FAILED(mIOThread->Dispatch(NS_NewRunnableFunction(
"nsSegmentedBuffer::FreeOMT",
[obj = mFreeOMT]() { obj->FreeAll(); })))) {
mFreeOMT->FreeAll();
}
}
void nsSegmentedBuffer::FreeOMTPointers::FreeAll() {
// Take all the tasks from the object. If AddTask is called after we release
// the lock, then another runnable will be dispatched for that task. This is
// necessary to avoid blocking the main thread while memory is being freed.
nsTArray<std::function<void()>> tasks = [this]() {
auto t = mTasks.Lock();
return std::move(*t);
}();
// Finally run all the tasks to free memory.
for (auto& task : tasks) {
task();
}
}
////////////////////////////////////////////////////////////////////////////////