[core] [node] pass thread pool impl to Map constructor

Updates mbgl::Map constructor usage everywhere

Adds NodeThreadPool implementation using AsyncQueue to call
Nan::AsyncQueueWorker from main thread

19 files changed, 183 insertions, 13 deletions

diff --git a/platform/android/config.cmake b/platform/android/config.cmake
index 1e6132dc30..74412e4ae5 100644
--- a/platform/android/config.cmake
+++ b/platform/android/config.cmake
@@ -48,6 +48,9 @@ macro(mbgl_platform_core)
 
         # Headless view
         # TODO
+
+        # Thread pool
+        PRIVATE platform/default/thread_pool.cpp
     )
 
     target_include_directories(mbgl-core
diff --git a/platform/android/src/native_map_view.cpp b/platform/android/src/native_map_view.cpp
index 2714b832e3..5bd2694932 100755
--- a/platform/android/src/native_map_view.cpp
+++ b/platform/android/src/native_map_view.cpp
@@ -60,7 +60,8 @@ NativeMapView::NativeMapView(JNIEnv *env_, jobject obj_, float pixelRatio_, int
       env(env_),
       pixelRatio(pixelRatio_),
       availableProcessors(availableProcessors_),
-      totalMemory(totalMemory_) {
+      totalMemory(totalMemory_),
+      threadPool(4) {
     mbgl::Log::Debug(mbgl::Event::Android, "NativeMapView::NativeMapView");
 
     assert(env_ != nullptr);
@@ -81,7 +82,7 @@ NativeMapView::NativeMapView(JNIEnv *env_, jobject obj_, float pixelRatio_, int
         mbgl::android::cachePath + "/mbgl-offline.db",
         mbgl::android::apkPath);
 
-    map = std::make_unique<mbgl::Map>(*this, *fileSource, MapMode::Continuous);
+    map = std::make_unique<mbgl::Map>(*this, *fileSource, threadPool, MapMode::Continuous);
 
     float zoomFactor   = map->getMaxZoom() - map->getMinZoom() + 1;
     float cpuFactor    = availableProcessors;
diff --git a/platform/android/src/native_map_view.hpp b/platform/android/src/native_map_view.hpp
index 7974f282d9..d42890dae2 100755
--- a/platform/android/src/native_map_view.hpp
+++ b/platform/android/src/native_map_view.hpp
@@ -3,6 +3,7 @@
 #include <mbgl/map/map.hpp>
 #include <mbgl/map/view.hpp>
 #include <mbgl/util/noncopyable.hpp>
+#include <mbgl/platform/default/thread_pool.hpp>
 #include <mbgl/storage/default_file_source.hpp>
 
 #include <string>
@@ -95,6 +96,7 @@ private:
 
     // Ensure these are initialised last
     std::unique_ptr<mbgl::DefaultFileSource> fileSource;
+    mbgl::ThreadPool threadPool;
     std::unique_ptr<mbgl::Map> map;
     mbgl::EdgeInsets insets;
 
diff --git a/platform/default/thread_pool.cpp b/platform/default/thread_pool.cpp
new file mode 100644
index 0000000000..7108312c58
--- /dev/null
+++ b/platform/default/thread_pool.cpp
@@ -0,0 +1,55 @@
+#include <mbgl/platform/default/thread_pool.hpp>
+#include <mbgl/actor/mailbox.hpp>
+
+namespace mbgl {
+
+ThreadPool::ThreadPool(std::size_t count) {
+    threads.reserve(count);
+    for (std::size_t i = 0; i < count; ++i) {
+        threads.emplace_back([this] () {
+            while (true) {
+                std::unique_lock<std::mutex> lock(mutex);
+
+                cv.wait(lock, [this] {
+                    return !queue.empty() || terminate;
+                });
+
+                if (terminate) {
+                    return;
+                }
+
+                auto mailbox = queue.front();
+                queue.pop();
+                lock.unlock();
+
+                if (auto locked = mailbox.lock()) {
+                    locked->receive();
+                }
+            }
+        });
+    }
+}
+
+ThreadPool::~ThreadPool() {
+    {
+        std::lock_guard<std::mutex> lock(mutex);
+        terminate = true;
+    }
+
+    cv.notify_all();
+
+    for (auto& thread : threads) {
+        thread.join();
+    }
+}
+
+void ThreadPool::schedule(std::weak_ptr<Mailbox> mailbox) {
+    {
+        std::lock_guard<std::mutex> lock(mutex);
+        queue.push(mailbox);
+    }
+
+    cv.notify_one();
+}
+
+} // namespace mbgl
diff --git a/platform/ios/config.cmake b/platform/ios/config.cmake
index 6c83395a3e..e5480e37df 100644
--- a/platform/ios/config.cmake
+++ b/platform/ios/config.cmake
@@ -40,6 +40,9 @@ macro(mbgl_platform_core)
         PRIVATE platform/darwin/src/headless_view_eagl.mm
         PRIVATE platform/default/headless_display.cpp
         PRIVATE platform/default/headless_view.cpp
+
+        # Thread pool
+        PRIVATE platform/default/thread_pool.cpp
     )
 
     target_add_mason_package(mbgl-core PUBLIC geojson)
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index 88f4d8a970..194f1a88d4 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -13,6 +13,7 @@
 #include <mbgl/map/mode.hpp>
 #include <mbgl/platform/platform.hpp>
 #include <mbgl/platform/darwin/reachability.h>
+#include <mbgl/platform/default/thread_pool.hpp>
 #include <mbgl/storage/default_file_source.hpp>
 #include <mbgl/storage/network_status.hpp>
 #include <mbgl/style/transition_options.hpp>
@@ -258,6 +259,7 @@ public:
 {
     mbgl::Map *_mbglMap;
     MBGLView *_mbglView;
+    mbgl::ThreadPool *_mbglThreadPool;
 
     BOOL _opaque;
 
@@ -397,7 +399,8 @@ public:
 
     // setup mbgl map
     mbgl::DefaultFileSource *mbglFileSource = [MGLOfflineStorage sharedOfflineStorage].mbglFileSource;
-    _mbglMap = new mbgl::Map(*_mbglView, *mbglFileSource, mbgl::MapMode::Continuous, mbgl::GLContextMode::Unique, mbgl::ConstrainMode::None, mbgl::ViewportMode::Default);
+    _mbglThreadPool = new mbgl::ThreadPool(4);
+    _mbglMap = new mbgl::Map(*_mbglView, *mbglFileSource, *_mbglThreadPool, mbgl::MapMode::Continuous, mbgl::GLContextMode::Unique, mbgl::ConstrainMode::None, mbgl::ViewportMode::Default);
     [self validateTileCacheSize];
 
     // start paused if in IB
@@ -650,6 +653,12 @@ public:
         _mbglView = nullptr;
     }
 
+    if (_mbglThreadPool)
+    {
+        delete _mbglThreadPool;
+        _mbglThreadPool = nullptr;
+    }
+
     if ([[EAGLContext currentContext] isEqual:_context])
     {
         [EAGLContext setCurrentContext:nil];
diff --git a/platform/linux/config.cmake b/platform/linux/config.cmake
index 050a03bcb2..86e8697f8c 100644
--- a/platform/linux/config.cmake
+++ b/platform/linux/config.cmake
@@ -44,6 +44,9 @@ macro(mbgl_platform_core)
         PRIVATE platform/default/headless_display.cpp
         PRIVATE platform/default/headless_view.cpp
         PRIVATE platform/default/headless_view_glx.cpp
+
+        # Thread pool
+        PRIVATE platform/default/thread_pool.cpp
     )
 
     target_include_directories(mbgl-core
diff --git a/platform/macos/config.cmake b/platform/macos/config.cmake
index f8d4ab398f..645feb90c3 100644
--- a/platform/macos/config.cmake
+++ b/platform/macos/config.cmake
@@ -38,6 +38,9 @@ macro(mbgl_platform_core)
         PRIVATE platform/darwin/src/headless_view_cgl.cpp
         PRIVATE platform/default/headless_display.cpp
         PRIVATE platform/default/headless_view.cpp
+
+        # Thread pool
+        PRIVATE platform/default/thread_pool.cpp
     )
 
     target_add_mason_package(mbgl-core PUBLIC geojson)
diff --git a/platform/macos/src/MGLMapView.mm b/platform/macos/src/MGLMapView.mm
index a8f91a24e7..46766b573b 100644
--- a/platform/macos/src/MGLMapView.mm
+++ b/platform/macos/src/MGLMapView.mm
@@ -22,6 +22,7 @@
 #import <mbgl/annotation/annotation.hpp>
 #import <mbgl/map/camera.hpp>
 #import <mbgl/platform/darwin/reachability.h>
+#import <mbgl/platform/default/thread_pool.hpp>
 #import <mbgl/gl/extension.hpp>
 #import <mbgl/gl/gl.hpp>
 #import <mbgl/sprite/sprite_image.hpp>
@@ -158,6 +159,7 @@ public:
     /// Cross-platform map view controller.
     mbgl::Map *_mbglMap;
     MGLMapViewImpl *_mbglView;
+    mbgl::ThreadPool *_mbglThreadPool;
 
     NSPanGestureRecognizer *_panGestureRecognizer;
     NSMagnificationGestureRecognizer *_magnificationGestureRecognizer;
@@ -261,7 +263,8 @@ public:
     [[NSFileManager defaultManager] removeItemAtURL:legacyCacheURL error:NULL];
 
     mbgl::DefaultFileSource *mbglFileSource = [MGLOfflineStorage sharedOfflineStorage].mbglFileSource;
-    _mbglMap = new mbgl::Map(*_mbglView, *mbglFileSource, mbgl::MapMode::Continuous, mbgl::GLContextMode::Unique, mbgl::ConstrainMode::None, mbgl::ViewportMode::Default);
+    _mbglThreadPool = new mbgl::ThreadPool(4);
+    _mbglMap = new mbgl::Map(*_mbglView, *mbglFileSource, *_mbglThreadPool, mbgl::MapMode::Continuous, mbgl::GLContextMode::Unique, mbgl::ConstrainMode::None, mbgl::ViewportMode::Default);
     [self validateTileCacheSize];
 
     // Install the OpenGL layer. Interface Builder’s synchronous drawing means
@@ -466,6 +469,10 @@ public:
         delete _mbglView;
         _mbglView = nullptr;
     }
+    if (_mbglThreadPool) {
+        delete _mbglThreadPool;
+        _mbglThreadPool = nullptr;
+    }
 }
 
 - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(__unused NSDictionary *)change context:(void *)context {
diff --git a/platform/node/src/node_log.cpp b/platform/node/src/node_log.cpp
index 5ea0bcc06a..0a97ebce36 100644
--- a/platform/node/src/node_log.cpp
+++ b/platform/node/src/node_log.cpp
@@ -1,5 +1,4 @@
 #include "node_log.hpp"
-#include "util/async_queue.hpp"
 
 #include <mbgl/util/enum.hpp>
 
@@ -19,7 +18,7 @@ struct NodeLogObserver::LogMessage {
 };
 
 NodeLogObserver::NodeLogObserver(v8::Local<v8::Object> target)
-    : queue(new Queue(uv_default_loop(), [this](LogMessage &message) {
+    : queue(new util::AsyncQueue<LogMessage>(uv_default_loop(), [this](LogMessage &message) {
           Nan::HandleScope scope;
 
           auto msg = Nan::New<v8::Object>();
diff --git a/platform/node/src/node_log.hpp b/platform/node/src/node_log.hpp
index d29e4e28e0..a19c61284b 100644
--- a/platform/node/src/node_log.hpp
+++ b/platform/node/src/node_log.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include "util/async_queue.hpp"
+
 #include <mbgl/platform/log.hpp>
 
 #pragma GCC diagnostic push
@@ -24,8 +26,7 @@ private:
     Nan::Persistent<v8::Object> module;
 
     struct LogMessage;
-    using Queue = util::AsyncQueue<LogMessage>;
-    Queue *queue = nullptr;
+    util::AsyncQueue<LogMessage>* queue;
 };
 
 }
diff --git a/platform/node/src/node_map.cpp b/platform/node/src/node_map.cpp
index 4d4be5be66..a13adbc417 100644
--- a/platform/node/src/node_map.cpp
+++ b/platform/node/src/node_map.cpp
@@ -777,7 +777,8 @@ NodeMap::NodeMap(v8::Local<v8::Object> options) :
         Nan::HandleScope scope;
         return Nan::Has(options, Nan::New("ratio").ToLocalChecked()).FromJust() ? Nan::Get(options, Nan::New("ratio").ToLocalChecked()).ToLocalChecked()->NumberValue() : 1.0;
     }()),
-    map(std::make_unique<mbgl::Map>(view, *this, mbgl::MapMode::Still)),
+    threadpool(),
+    map(std::make_unique<mbgl::Map>(view, *this, threadpool, mbgl::MapMode::Still)),
     async(new uv_async_t) {
 
     view.setMapChangeCallback([&](mbgl::MapChange change) {
diff --git a/platform/node/src/node_map.hpp b/platform/node/src/node_map.hpp
index c0b025c369..cdca1587ea 100644
--- a/platform/node/src/node_map.hpp
+++ b/platform/node/src/node_map.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include "node_thread_pool.hpp"
+
 #include <mbgl/map/map.hpp>
 #include <mbgl/storage/file_source.hpp>
 #include <mbgl/platform/default/headless_view.hpp>
@@ -52,6 +54,7 @@ public:
     std::unique_ptr<mbgl::AsyncRequest> request(const mbgl::Resource&, mbgl::FileSource::Callback);
 
     mbgl::HeadlessView view;
+    NodeThreadPool threadpool;
     std::unique_ptr<mbgl::Map> map;
 
     std::exception_ptr error;
diff --git a/platform/node/src/node_thread_pool.cpp b/platform/node/src/node_thread_pool.cpp
new file mode 100644
index 0000000000..a9faef6f09
--- /dev/null
+++ b/platform/node/src/node_thread_pool.cpp
@@ -0,0 +1,39 @@
+#include "node_thread_pool.hpp"
+#include "util/async_queue.hpp"
+
+#include <mbgl/actor/mailbox.hpp>
+
+namespace node_mbgl {
+
+NodeThreadPool::NodeThreadPool()
+    : queue(new util::AsyncQueue<std::weak_ptr<mbgl::Mailbox>>(uv_default_loop(), [this](std::weak_ptr<mbgl::Mailbox> mailbox) {
+        Worker* worker = new Worker(mailbox);
+        Nan::AsyncQueueWorker(worker);
+    })) {
+    // Don't keep the event loop alive.
+    queue->unref();
+}
+
+NodeThreadPool::~NodeThreadPool() {
+    queue->stop();
+}
+
+void NodeThreadPool::schedule(std::weak_ptr<mbgl::Mailbox> mailbox) {
+    queue->send(std::move(mailbox));
+}
+
+NodeThreadPool::Worker::Worker(std::weak_ptr<mbgl::Mailbox> mailbox_)
+    : AsyncWorker(nullptr),
+    mailbox(std::move(mailbox_)) {};
+
+void NodeThreadPool::Worker::Execute() {
+    if (auto locked = mailbox.lock()) {
+        locked->receive();
+    }
+}
+
+void NodeThreadPool::Worker::WorkComplete() {
+    // no-op to avoid calling nullptr callback
+}
+
+} // namespace node_mbgl
diff --git a/platform/node/src/node_thread_pool.hpp b/platform/node/src/node_thread_pool.hpp
new file mode 100644
index 0000000000..d412e53d3d
--- /dev/null
+++ b/platform/node/src/node_thread_pool.hpp
@@ -0,0 +1,37 @@
+#pragma once
+
+#include <mbgl/actor/scheduler.hpp>
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#pragma GCC diagnostic ignored "-Wshadow"
+#include <nan.h>
+#pragma GCC diagnostic pop
+
+namespace node_mbgl {
+
+namespace util { template <typename T> class AsyncQueue; }
+
+class NodeThreadPool : public mbgl::Scheduler {
+public:
+    NodeThreadPool();
+    ~NodeThreadPool();
+
+    void schedule(std::weak_ptr<mbgl::Mailbox>) override;
+
+private:
+    util::AsyncQueue<std::weak_ptr<mbgl::Mailbox>>* queue;
+
+    class Worker : public Nan::AsyncWorker {
+    public:
+        Worker(std::weak_ptr<mbgl::Mailbox>);
+
+        void Execute();
+        void WorkComplete();
+
+    private:
+        std::weak_ptr<mbgl::Mailbox> mailbox;
+    };
+};
+
+} // namespace node_mbgl
diff --git a/platform/node/src/util/async_queue.hpp b/platform/node/src/util/async_queue.hpp
index b9081b3aeb..87737437c3 100644
--- a/platform/node/src/util/async_queue.hpp
+++ b/platform/node/src/util/async_queue.hpp
@@ -28,6 +28,7 @@ public:
             q->process();
         });
     }
+    ~AsyncQueue() {}
 
     void send(T &&data) {
         {
@@ -60,9 +61,6 @@ public:
     }
 
 private:
-    ~AsyncQueue() {
-    }
-
     void process() {
         std::unique_ptr<T> item;
         while (true) {
diff --git a/platform/qt/qt.cmake b/platform/qt/qt.cmake
index dc60455b0a..398e173cfa 100644
--- a/platform/qt/qt.cmake
+++ b/platform/qt/qt.cmake
@@ -30,6 +30,9 @@ set(MBGL_QT_FILES
     # Misc
     PRIVATE platform/default/log_stderr.cpp
 
+    # Thread pool
+    PRIVATE platform/default/thread_pool.cpp
+
     # Platform integration
     PRIVATE platform/qt/src/async_task.cpp
     PRIVATE platform/qt/src/async_task_impl.hpp
diff --git a/platform/qt/src/qmapboxgl.cpp b/platform/qt/src/qmapboxgl.cpp
index 103ed83256..d0a05301f8 100644
--- a/platform/qt/src/qmapboxgl.cpp
+++ b/platform/qt/src/qmapboxgl.cpp
@@ -811,8 +811,9 @@ QMapboxGLPrivate::QMapboxGLPrivate(QMapboxGL *q, const QMapboxGLSettings &settin
         settings.cacheDatabasePath().toStdString(),
         settings.assetPath().toStdString(),
         settings.cacheDatabaseMaximumSize()))
+    , threadPool(4)
     , mapObj(std::make_unique<mbgl::Map>(
-        *this, *fileSourceObj,
+        *this, *fileSourceObj, threadPool,
         static_cast<mbgl::MapMode>(settings.mapMode()),
         static_cast<mbgl::GLContextMode>(settings.contextMode()),
         static_cast<mbgl::ConstrainMode>(settings.constrainMode()),
diff --git a/platform/qt/src/qmapboxgl_p.hpp b/platform/qt/src/qmapboxgl_p.hpp
index 11b5f695ca..c35ac4e7ba 100644
--- a/platform/qt/src/qmapboxgl_p.hpp
+++ b/platform/qt/src/qmapboxgl_p.hpp
@@ -4,6 +4,7 @@
 
 #include <mbgl/map/map.hpp>
 #include <mbgl/map/view.hpp>
+#include <mbgl/platform/default/thread_pool.hpp>
 #include <mbgl/storage/default_file_source.hpp>
 #include <mbgl/util/geo.hpp>
 
@@ -34,6 +35,7 @@ public:
     QMapboxGL *q_ptr { nullptr };
 
     std::unique_ptr<mbgl::DefaultFileSource> fileSourceObj;
+    mbgl::ThreadPool threadPool;
     std::unique_ptr<mbgl::Map> mapObj;
 
     bool dirty { false };