AU: Watch for writes on write fds only, and for reads on read fds.
This reduces the CPU load from 100% to 0% when staying idle waiting for a server
response.
BUG=8200
TEST=unit tests, tested on device
Change-Id: I07216076753b4b0dea9672470f1a6d572482f9a2
Review URL: http://codereview.chromium.org/4190009
diff --git a/libcurl_http_fetcher.cc b/libcurl_http_fetcher.cc
index a921725..8af9d45 100644
--- a/libcurl_http_fetcher.cc
+++ b/libcurl_http_fetcher.cc
@@ -228,55 +228,71 @@
void LibcurlHttpFetcher::SetupMainloopSources() {
fd_set fd_read;
fd_set fd_write;
- fd_set fd_exec;
+ fd_set fd_exc;
FD_ZERO(&fd_read);
FD_ZERO(&fd_write);
- FD_ZERO(&fd_exec);
+ FD_ZERO(&fd_exc);
int fd_max = 0;
// Ask libcurl for the set of file descriptors we should track on its
// behalf.
CHECK_EQ(curl_multi_fdset(curl_multi_handle_, &fd_read, &fd_write,
- &fd_exec, &fd_max), CURLM_OK);
+ &fd_exc, &fd_max), CURLM_OK);
// We should iterate through all file descriptors up to libcurl's fd_max or
- // the highest one we're tracking, whichever is larger
- if (!io_channels_.empty())
- fd_max = max(fd_max, io_channels_.rbegin()->first);
+ // the highest one we're tracking, whichever is larger.
+ for (size_t t = 0; t < arraysize(io_channels_); ++t) {
+ if (!io_channels_[t].empty())
+ fd_max = max(fd_max, io_channels_[t].rbegin()->first);
+ }
- // For each fd, if we're not tracking it, track it. If we are tracking it,
- // but libcurl doesn't care about it anymore, stop tracking it.
- // After this loop, there should be exactly as many GIOChannel objects
- // in io_channels_ as there are fds that we're tracking.
- for (int i = 0; i <= fd_max; i++) {
- if (!(FD_ISSET(i, &fd_read) || FD_ISSET(i, &fd_write) ||
- FD_ISSET(i, &fd_exec))) {
- // if we have an outstanding io_channel, remove it
- if (io_channels_.find(i) != io_channels_.end()) {
- g_source_remove(io_channels_[i].second);
- g_io_channel_unref(io_channels_[i].first);
- io_channels_.erase(io_channels_.find(i));
+ // For each fd, if we're not tracking it, track it. If we are tracking it, but
+ // libcurl doesn't care about it anymore, stop tracking it. After this loop,
+ // there should be exactly as many GIOChannel objects in io_channels_[0|1] as
+ // there are read/write fds that we're tracking.
+ for (int fd = 0; fd <= fd_max; ++fd) {
+ // Note that fd_exc is unused in the current version of libcurl so is_exc
+ // should always be false.
+ bool is_exc = FD_ISSET(fd, &fd_exc) != 0;
+ bool must_track[2] = {
+ is_exc || (FD_ISSET(fd, &fd_read) != 0), // track 0 -- read
+ is_exc || (FD_ISSET(fd, &fd_write) != 0) // track 1 -- write
+ };
+
+ for (size_t t = 0; t < arraysize(io_channels_); ++t) {
+ bool tracked = io_channels_[t].find(fd) != io_channels_[t].end();
+
+ if (!must_track[t]) {
+ // If we have an outstanding io_channel, remove it.
+ if (tracked) {
+ g_source_remove(io_channels_[t][fd].second);
+ g_io_channel_unref(io_channels_[t][fd].first);
+ io_channels_[t].erase(io_channels_[t].find(fd));
+ }
+ continue;
}
- continue;
- }
- // If we are already tracking this fd, continue.
- if (io_channels_.find(i) != io_channels_.end())
- continue;
- // We must track a new fd
- GIOChannel *io_channel = g_io_channel_unix_new(i);
- guint tag = g_io_add_watch(
- io_channel,
- static_cast<GIOCondition>(G_IO_IN | G_IO_OUT | G_IO_PRI |
- G_IO_ERR | G_IO_HUP),
- &StaticFDCallback,
- this);
- io_channels_[i] = make_pair(io_channel, tag);
- static int io_counter = 0;
- io_counter++;
- if (io_counter % 50 == 0) {
- LOG(INFO) << "io_counter = " << io_counter;
+
+ // If we are already tracking this fd, continue -- nothing to do.
+ if (tracked)
+ continue;
+
+ // Set conditions appropriately -- read for track 0, write for track 1.
+ GIOCondition condition = static_cast<GIOCondition>(
+ ((t == 0) ? (G_IO_IN | G_IO_PRI) : G_IO_OUT) | G_IO_ERR | G_IO_HUP);
+
+ // Track a new fd.
+ GIOChannel* io_channel = g_io_channel_unix_new(fd);
+ guint tag =
+ g_io_add_watch(io_channel, condition, &StaticFDCallback, this);
+
+ io_channels_[t][fd] = make_pair(io_channel, tag);
+ static int io_counter = 0;
+ io_counter++;
+ if (io_counter % 50 == 0) {
+ LOG(INFO) << "io_counter = " << io_counter;
+ }
}
}
@@ -321,12 +337,14 @@
timeout_source_ = NULL;
}
- for (IOChannels::iterator it = io_channels_.begin();
- it != io_channels_.end(); ++it) {
- g_source_remove(it->second.second);
- g_io_channel_unref(it->second.first);
+ for (size_t t = 0; t < arraysize(io_channels_); ++t) {
+ for (IOChannels::iterator it = io_channels_[t].begin();
+ it != io_channels_[t].end(); ++it) {
+ g_source_remove(it->second.second);
+ g_io_channel_unref(it->second.first);
+ }
+ io_channels_[t].clear();
}
- io_channels_.clear();
if (curl_handle_) {
if (curl_multi_handle_) {