Stop ServiceWorker context when no controllee is associated (and when all refs are dropped)

content/browser/service_worker/service_worker_version.cc

Index: content/browser/service_worker/service_worker_version.cc
diff --git a/content/browser/service_worker/service_worker_version.cc b/content/browser/service_worker/service_worker_version.cc
index 0bcec8983900ca78b5beb9bd25191707c4c7138b..27ff20619ed487f665e37208a043ac0bd7cfd68d 100644
--- a/content/browser/service_worker/service_worker_version.cc
+++ b/content/browser/service_worker/service_worker_version.cc
@@ -11,6 +11,7 @@
 #include "content/browser/service_worker/embedded_worker_registry.h"
 #include "content/browser/service_worker/service_worker_context_core.h"
 #include "content/browser/service_worker/service_worker_registration.h"
+#include "content/browser/service_worker/service_worker_utils.h"
 #include "content/common/service_worker/service_worker_messages.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/common/content_switches.h"
@@ -22,6 +23,12 @@ typedef ServiceWorkerVersion::MessageCallback MessageCallback;
 
 namespace {
 
+// Default delay to stop the worker context after all documents that
+// are associated to the worker are closed.
+// (Note that if all references to the version is dropped the worker
+// is also stopped without delay)
+const int64 kStopWorkerDelay = 5 * 60;  // 5 mins.

[Jeffrey Yasskin, 2014/05/15 19:16:44]

We should probably make this faster. Extension/App event pages die after 15
seconds of no events, which indicates that a short-ish timeout works for some
people. The counter-indication is that extension/app authors can extend their
event page's lifetime by calling various callback APIs, which we don't want to
allow in SWs. Even so, we don't really want someone using 5 minutes of CPU after
their last tab is closed or they handle the most recent event.

We're also going to need to make this delay configurable from devtools.

[kinuko, 2014/05/16 04:13:51]

I don't have a strong opinion on this delay for now, let me change this to
default to 30 secs for now.
Let us do this in a separate patch.

+
 void RunSoon(const base::Closure& callback) {
   if (!callback.is_null())
     base::MessageLoop::current()->PostTask(FROM_HERE, callback);
@@ -103,10 +110,13 @@ ServiceWorkerVersion::ServiceWorkerVersion(
 }
 
 ServiceWorkerVersion::~ServiceWorkerVersion() {
-  if (embedded_worker_) {
-    embedded_worker_->RemoveListener(this);
-    embedded_worker_.reset();
+  if (running_status() == RUNNING) {
+    if (stop_worker_timer_.IsRunning())
+      stop_worker_timer_.Stop();

[michaeln, 2014/05/15 19:02:20]

base::Timer's destructor takes care of this

[kinuko, 2014/05/16 04:13:51]

Oh yeah that's handy...

   }
+  embedded_worker_->RemoveListener(this);
+  // EmbeddedWorker's dtor sends StopWorker if it's still running.
+  embedded_worker_.reset();

[michaeln, 2014/05/15 19:02:20]

is the call to .reset() needed for ordering reasons, if not might be nice to
remove it.

can this method could be simplified to...

ServiceWorkerVersion::~ServiceWorkerVersion() {
  embedded_worker_->RemoveListener(this);
  if (context_)
    context_->RemoveLiveVersion(version_id_);
}

[kinuko, 2014/05/16 04:13:51]

Done.

   if (context_)
     context_->RemoveLiveVersion(version_id_);
 }
@@ -148,7 +158,6 @@ void ServiceWorkerVersion::StartWorker(const StatusCallback& callback) {
 void ServiceWorkerVersion::StartWorkerWithCandidateProcesses(
     const std::vector<int>& possible_process_ids,
     const StatusCallback& callback) {
-  DCHECK(embedded_worker_);
   switch (running_status()) {
     case RUNNING:
       RunSoon(base::Bind(callback, SERVICE_WORKER_OK));
@@ -173,7 +182,6 @@ void ServiceWorkerVersion::StartWorkerWithCandidateProcesses(
 }
 
 void ServiceWorkerVersion::StopWorker(const StatusCallback& callback) {
-  DCHECK(embedded_worker_);
   if (running_status() == STOPPED) {
     RunSoon(base::Bind(callback, SERVICE_WORKER_OK));
     return;
@@ -190,7 +198,6 @@ void ServiceWorkerVersion::StopWorker(const StatusCallback& callback) {
 
 void ServiceWorkerVersion::SendMessage(
     const IPC::Message& message, const StatusCallback& callback) {
-  DCHECK(embedded_worker_);
   if (running_status() != RUNNING) {
     // Schedule calling this method after starting the worker.
     StartWorker(base::Bind(&RunTaskAfterStartWorker,
@@ -318,6 +325,8 @@ void ServiceWorkerVersion::AddControllee(
   int controllee_id = controllee_by_id_.Add(provider_host);
   controllee_map_[provider_host] = controllee_id;
   AddProcessToWorker(provider_host->process_id());
+  if (stop_worker_timer_.IsRunning())
+    stop_worker_timer_.Stop();
 }
 
 void ServiceWorkerVersion::RemoveControllee(
@@ -327,6 +336,8 @@ void ServiceWorkerVersion::RemoveControllee(
   controllee_by_id_.Remove(found->second);
   controllee_map_.erase(found);
   RemoveProcessFromWorker(provider_host->process_id());
+  if (!HasControllee())
+    ScheduleStopWorker();

[Jeffrey Yasskin, 2014/05/15 19:16:44]

No need to handle this in this CL, but we're going to need non-controllee events
like 'push' and 'sync' to be able to keep a SW alive too.

[kinuko, 2014/05/16 04:13:51]

Yeah we could add similar code in other events / upon completion of event
handlers too.

   // TODO(kinuko): Fire NoControllees notification when the # of controllees
   // reaches 0, so that a new pending version can be activated (which will
   // deactivate this version).
@@ -565,4 +576,18 @@ void ServiceWorkerVersion::OnPostMessageToDocument(
   provider_host->PostMessage(message, sent_message_port_ids);
 }
 
+void ServiceWorkerVersion::ScheduleStopWorker() {
+  if (running_status() != RUNNING)
+    return;
+  if (stop_worker_timer_.IsRunning()) {
+    stop_worker_timer_.Reset();

[michaeln, 2014/05/15 19:02:20]

nit: maybe prefer early return here

[kinuko, 2014/05/16 04:13:51]

Done.

+  } else {
+    stop_worker_timer_.Start(
+        FROM_HERE, base::TimeDelta::FromSeconds(kStopWorkerDelay),
+        base::Bind(&ServiceWorkerVersion::StopWorker,
+                   weak_factory_.GetWeakPtr(),
+                   base::Bind(&ServiceWorkerUtils::NoOpStatusCallback)));
+  }
+}
+
 }  // namespace content