?

上一次說(shuō)到通過(guò)管道把接收到的 HTTP 數(shù)據(jù)通知另一個(gè)線程處理，它不是直接發(fā)送數(shù)據(jù)過(guò)去，而是把數(shù)據(jù)在共享內(nèi)存里的句柄發(fā)送過(guò)去，達(dá)到高效通訊的目的。下面就來(lái)分析資源處理進(jìn)程里，接收到這個(gè)消息之后，做些什么處理。這個(gè)消息的處理代碼如下：

?

#001 ? void ResourceDispatcher::OnReceivedData(int request_id,

#002 ????????????????????????????????????????? SharedMemoryHandle shm_handle,

#003 ????????????????????????????????????????? int data_len) {

#004 ??? // Acknowlegde the reception of this data.

回應(yīng)這個(gè)消息，說(shuō)已經(jīng)收到數(shù)據(jù)了。

#005 ??? IPC::Message::Sender* sender = message_sender();

#006 ??? if (sender)

#007 ????? sender->Send(

#008 ????????? new ViewHostMsg_DataReceived_ACK(MSG_ROUTING_NONE, request_id));

#009 ?

#010 ??? DCHECK((shm_handle && data_len > 0) || (!shm_handle && !data_len));

?

打開(kāi)共享內(nèi)存文件，使用只讀的方式。

#011 ??? SharedMemory shared_mem(shm_handle, true); ? // read only

#012 ?

?

查找到請(qǐng)求下載的資源的請(qǐng)求標(biāo)識(shí)號(hào)。

#013 ??? PendingRequestList::iterator it = pending_requests_.find(request_id);

?

如果沒(méi)有找到相應(yīng)的請(qǐng)求標(biāo)識(shí)號(hào)，就直接返回，不用處理這些數(shù)據(jù)。

#014 ??? if (it == pending_requests_.end()) {

#015 ????? // this might happen for kill()ed requests on the webkit end, so perhaps

#016 ????? // it shouldn't be a warning...

#017 ????? DLOG(WARNING) << "Got data for a nonexistant or finished request";

#018 ????? return;

#019 ??? }

#020 ?

?

這里找到相應(yīng)的請(qǐng)求標(biāo)識(shí)號(hào)，就把數(shù)據(jù)放到請(qǐng)求信息里處理。

#021 ??? PendingRequestInfo& request_info = it->second;

#022 ?

#023 ??? if (data_len > 0 && shared_mem.Map(data_len)) {

#024 ????? RESOURCE_LOG("Dispatching " << data_len << " bytes for " <<

#025 ?????????????????? request_info.peer->GetURLForDebugging());

#026 ????? const char* data = static_cast<char*>(shared_mem.memory());

#027 ????? request_info.peer->OnReceivedData(data, data_len);

#028 ??? }

#029 ? }

?

上面這個(gè)函數(shù)實(shí)現(xiàn)接收到 HTTP 數(shù)據(jù)，并且把數(shù)據(jù)放到請(qǐng)求的緩沖區(qū)里，但它沒(méi)有知道什么時(shí)候接收數(shù)據(jù)完成，顯然有另外一個(gè)消息來(lái)做這些的工作，就是下面類 ResourceDispatcherHost 的函數(shù)：

?

#001 ??? bool OnResponseCompleted(int request_id, const URLRequestStatus& status) {

#002 ????? receiver_->Send(new ViewMsg_Resource_RequestComplete(

#003 ????????? routing_id_, request_id, status));

#004 ?

#005 ????? // If we still have a read buffer, then see about caching it for later...

#006 ????? if (spare_read_buffer_) {

#007 ??????? read_buffer_.reset();

#008 ????? } else if (read_buffer_.get() && read_buffer_->memory()) {

#009 ??????? spare_read_buffer_ = read_buffer_.release();

#010 ????? }

#011 ????? return true;

#012 ??? }

?

這個(gè)函數(shù)里通過(guò)發(fā)送消息 ViewMsg_Resource_RequestComplete 來(lái)通知資源進(jìn)程已經(jīng)把網(wǎng)絡(luò)的數(shù)據(jù)接收完成了，可以進(jìn)入下一步處理。然后在資源進(jìn)程里就會(huì)處理這個(gè)消息，下一次再來(lái)分析這方面的代碼。

谷歌瀏覽器的源碼分析(31)