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fix: race condition in NodeStreamLoader (#19811)

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* fix: race condition in NodeStreamLoader

* nit: add comments
This commit is contained in:
Heilig Benedek 2019-08-21 05:23:46 +02:00 committed by Cheng Zhao
parent b7defaaf6a
commit 3f49f984e6
2 changed files with 24 additions and 4 deletions
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19
shell/browser/net/node_stream_loader.cc
View file

@ -71,12 +71,18 @@ void NodeStreamLoader::Start(network::ResourceResponseHead head) {
base::BindRepeating(&NodeStreamLoader::NotifyComplete, weak, net::OK)); base::BindRepeating(&NodeStreamLoader::NotifyComplete, weak, net::OK));
On("error", base::BindRepeating(&NodeStreamLoader::NotifyComplete, weak, On("error", base::BindRepeating(&NodeStreamLoader::NotifyComplete, weak,
net::ERR_FAILED)); net::ERR_FAILED));
On("readable", base::BindRepeating(&NodeStreamLoader::ReadMore, weak)); On("readable", base::BindRepeating(&NodeStreamLoader::NotifyReadable, weak));
}
void NodeStreamLoader::NotifyReadable() {
if (!readable_)
ReadMore();
readable_ = true;
} }
void NodeStreamLoader::NotifyComplete(int result) { void NodeStreamLoader::NotifyComplete(int result) {
// Wait until write finishes or fails. // Wait until write finishes or fails.
if (is_writing_) { if (is_reading_ || is_writing_) {
ended_ = true; ended_ = true;
result_ = result; result_ = result;
return; return;
@ -87,19 +93,24 @@ void NodeStreamLoader::NotifyComplete(int result) {
} }
void NodeStreamLoader::ReadMore() { void NodeStreamLoader::ReadMore() {
is_reading_ = true;
// buffer = emitter.read() // buffer = emitter.read()
v8::MaybeLocal<v8::Value> ret = node::MakeCallback( v8::MaybeLocal<v8::Value> ret = node::MakeCallback(
isolate_, emitter_.Get(isolate_), "read", 0, nullptr, {0, 0}); isolate_, emitter_.Get(isolate_), "read", 0, nullptr, {0, 0});
// If there is no buffer read, wait until |readable| is emitted again. // If there is no buffer read, wait until |readable| is emitted again.
v8::Local<v8::Value> buffer; v8::Local<v8::Value> buffer;
if (!ret.ToLocal(&buffer) || !node::Buffer::HasInstance(buffer)) if (!ret.ToLocal(&buffer) || !node::Buffer::HasInstance(buffer)) {
readable_ = false;
is_reading_ = false;
return; return;
}
// Hold the buffer until the write is done. // Hold the buffer until the write is done.
buffer_.Reset(isolate_, buffer); buffer_.Reset(isolate_, buffer);
// Write buffer to mojo pipe asyncronously. // Write buffer to mojo pipe asyncronously.
is_reading_ = false;
is_writing_ = true; is_writing_ = true;
producer_->Write( producer_->Write(
std::make_unique<mojo::StringDataSource>( std::make_unique<mojo::StringDataSource>(
@ -118,7 +129,7 @@ void NodeStreamLoader::DidWrite(MojoResult result) {
return; return;
} }
if (result == MOJO_RESULT_OK) if (result == MOJO_RESULT_OK && readable_)
ReadMore(); ReadMore();
else else
NotifyComplete(net::ERR_FAILED); NotifyComplete(net::ERR_FAILED);

9
shell/browser/net/node_stream_loader.h
View file

@ -39,6 +39,7 @@ class NodeStreamLoader : public network::mojom::URLLoader {
using EventCallback = base::RepeatingCallback<void()>; using EventCallback = base::RepeatingCallback<void()>;
void Start(network::ResourceResponseHead head); void Start(network::ResourceResponseHead head);
void NotifyReadable();
void NotifyComplete(int result); void NotifyComplete(int result);
void ReadMore(); void ReadMore();
void DidWrite(MojoResult result); void DidWrite(MojoResult result);
@ -68,11 +69,19 @@ class NodeStreamLoader : public network::mojom::URLLoader {
// Whether we are in the middle of write. // Whether we are in the middle of write.
bool is_writing_ = false; bool is_writing_ = false;
// Whether we are in the middle of a stream.read().
bool is_reading_ = false;
// When NotifyComplete is called while writing, we will save the result and // When NotifyComplete is called while writing, we will save the result and
// quit with it after the write is done. // quit with it after the write is done.
bool ended_ = false; bool ended_ = false;
int result_ = net::OK; int result_ = net::OK;
// When the stream emits the readable event, we only want to start reading
// data if the stream was not readable before, so we store the state in a
// flag.
bool readable_ = false;
// Store the V8 callbacks to unsubscribe them later. // Store the V8 callbacks to unsubscribe them later.
std::map<std::string, v8::Global<v8::Value>> handlers_; std::map<std::string, v8::Global<v8::Value>> handlers_;