From 64251eec75dd4cd9ec6aacc1c1e7ecc379b8ad9e Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Thu, 30 Apr 2015 12:28:29 -0400
Subject: [PATCH] Introduce and use uv::timer

---
 platform/darwin/http_request_nsurl.mm | 44 +++++-----------------
 src/mbgl/util/uv_detail.hpp           | 54 +++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 34 deletions(-)

diff --git a/platform/darwin/http_request_nsurl.mm b/platform/darwin/http_request_nsurl.mm
index 9572970f2..509e158af 100644
--- a/platform/darwin/http_request_nsurl.mm
+++ b/platform/darwin/http_request_nsurl.mm
@@ -58,14 +58,11 @@ public:
     void retry() override;
 
 private:
-    void cancelTimer();
     void start();
     void handleResult(NSData *data, NSURLResponse *res, NSError *error);
     void handleResponse();
     void retry(uint64_t timeout);
 
-    static void restart(uv_timer_t *timer, int);
-
     HTTPNSURLContext *context = nullptr;
     bool cancelled = false;
     NSURLSessionDataTask *task = nullptr;
@@ -73,8 +70,8 @@ private:
     const std::shared_ptr<const Response> existingResponse;
     ResponseStatus status = ResponseStatus::PermanentError;
     uv::async async;
+    uv::timer timer;
     int attempts = 0;
-    uv_timer_t *timer = nullptr;
     enum : bool { PreemptImmediately, ExponentialBackoff } strategy = PreemptImmediately;
 
     static const int maxAttempts = 4;
@@ -134,7 +131,8 @@ HTTPRequest::HTTPRequest(HTTPNSURLContext* context_, const Resource& resource_,
     : RequestBase(resource_, callback_),
       context(context_),
       existingResponse(existingResponse_),
-      async(loop, [this] { handleResponse(); }) {
+      async(loop, [this] { handleResponse(); }),
+      timer(loop) {
     context->addRequest(this);
     start();
 }
@@ -143,7 +141,7 @@ HTTPRequest::~HTTPRequest() {
     assert(!task);
 
     // Stop the backoff timer to avoid re-triggering this request.
-    cancelTimer();
+    timer.stop();
 
     context->removeRequest(this);
 }
@@ -220,7 +218,7 @@ void HTTPRequest::cancel() {
     cancelled = true;
 
     // Stop the backoff timer to avoid re-triggering this request.
-    cancelTimer();
+    timer.stop();
 
     if (task) {
         [task cancel];
@@ -231,14 +229,6 @@ void HTTPRequest::cancel() {
     }
 }
 
-void HTTPRequest::cancelTimer() {
-    if (timer) {
-        uv_timer_stop(timer);
-        uv::close(timer);
-        timer = nullptr;
-    }
-}
-
 int64_t parseCacheControl(const char *value) {
     if (value) {
         unsigned long long seconds = 0;
@@ -360,34 +350,20 @@ void HTTPRequest::handleResult(NSData *data, NSURLResponse *res, NSError *error)
 void HTTPRequest::retry(uint64_t timeout) {
     response.reset();
 
-    assert(!timer);
-    timer = new uv_timer_t;
-    timer->data = this;
-    uv_timer_init(async.get()->loop, timer);
-    uv_timer_start(timer, restart, timeout, 0);
+    timer.stop();
+    timer.start(timeout, 0, [this] { start(); });
 }
 
 void HTTPRequest::retry() {
     // All batons get notified when the network status changed, but some of them
     // might not actually wait for the network to become available again.
-    if (timer && strategy == PreemptImmediately) {
+    if (strategy == PreemptImmediately) {
         // Triggers the timer upon the next event loop iteration.
-        uv_timer_stop(timer);
-        uv_timer_start(timer, restart, 0, 0);
+        timer.stop();
+        timer.start(0, 0, [this] { start(); });
     }
 }
 
-void HTTPRequest::restart(uv_timer_t *timer, int) {
-    // Restart the request.
-    auto impl = reinterpret_cast<HTTPRequest *>(timer->data);
-
-    // Get rid of the timer.
-    impl->timer = nullptr;
-    uv::close(timer);
-
-    impl->start();
-}
-
 std::unique_ptr<HTTPContext> HTTPContext::createContext(uv_loop_t* loop) {
     return util::make_unique<HTTPNSURLContext>(loop);
 }
diff --git a/src/mbgl/util/uv_detail.hpp b/src/mbgl/util/uv_detail.hpp
index fbc0ec5aa..f77bec0fa 100644
--- a/src/mbgl/util/uv_detail.hpp
+++ b/src/mbgl/util/uv_detail.hpp
@@ -121,6 +121,60 @@ private:
     std::function<void ()> fn;
 };
 
+class timer : public mbgl::util::noncopyable {
+public:
+    inline timer(uv_loop_t* loop)
+        : t(new uv_timer_t)
+    {
+        t->data = this;
+        if (uv_timer_init(loop, t.get()) != 0) {
+            throw std::runtime_error("failed to initialize timer");
+        }
+    }
+
+    inline timer() {
+        close(std::move(t));
+    }
+
+    inline void start(uint64_t timeout, uint64_t repeat, std::function<void ()> fn_) {
+        fn = fn_;
+        if (uv_timer_start(t.get(), timer_cb, timeout, repeat) != 0) {
+            throw std::runtime_error("failed to start timer");
+        }
+    }
+
+    inline void stop() {
+        fn = nullptr;
+        if (uv_timer_stop(t.get()) != 0) {
+            throw std::runtime_error("failed to stop timer");
+        }
+    }
+
+    inline void ref() {
+        uv_ref(reinterpret_cast<uv_handle_t*>(t.get()));
+    }
+
+    inline void unref() {
+        uv_unref(reinterpret_cast<uv_handle_t*>(t.get()));
+    }
+
+    inline uv_timer_t* get() {
+        return t.get();
+    }
+
+private:
+#if UV_VERSION_MAJOR == 0 && UV_VERSION_MINOR <= 10
+    static void timer_cb(uv_timer_t* t, int) {
+#else
+    static void timer_cb(uv_timer_t* t) {
+#endif
+        reinterpret_cast<timer*>(t->data)->fn();
+    }
+
+    std::unique_ptr<uv_timer_t> t;
+    std::function<void ()> fn;
+};
+
 class mutex : public mbgl::util::noncopyable {
 public:
     inline mutex() {