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#include <mbgl/actor/actor.hpp>
#include <mbgl/actor/scheduler.hpp>
#include <mbgl/platform/settings.hpp>
#include <mbgl/storage/file_source_manager.hpp>
#include <mbgl/storage/file_source_request.hpp>
#include <mbgl/storage/main_resource_loader.hpp>
#include <mbgl/storage/resource.hpp>
#include <mbgl/storage/resource_options.hpp>
#include <mbgl/util/stopwatch.hpp>
#include <mbgl/util/thread.hpp>
#include <cassert>
#include <map>
namespace mbgl {
class MainResourceLoaderThread {
public:
MainResourceLoaderThread(std::shared_ptr<FileSource> assetFileSource_,
std::shared_ptr<FileSource> databaseFileSource_,
std::shared_ptr<FileSource> localFileSource_,
std::shared_ptr<FileSource> onlineFileSource_)
: assetFileSource(std::move(assetFileSource_)),
databaseFileSource(std::move(databaseFileSource_)),
localFileSource(std::move(localFileSource_)),
onlineFileSource(std::move(onlineFileSource_)) {}
void request(AsyncRequest* req, Resource resource, ActorRef<FileSourceRequest> ref) {
auto callback = [ref](const Response& res) { ref.invoke(&FileSourceRequest::setResponse, res); };
auto requestFromNetwork = [=](const Resource& res,
std::unique_ptr<AsyncRequest> parent) -> std::unique_ptr<AsyncRequest> {
if (!onlineFileSource || !onlineFileSource->canRequest(resource)) {
return parent;
}
// Keep parent request alive while chained request is being processed.
std::shared_ptr<AsyncRequest> parentKeepAlive = std::move(parent);
MBGL_TIMING_START(watch);
return onlineFileSource->request(res, [=, ptr = parentKeepAlive](Response response) {
if (databaseFileSource) {
databaseFileSource->forward(res, response);
}
if (res.kind == Resource::Kind::Tile) {
// onlineResponse.data will be null if data not modified
MBGL_TIMING_FINISH(watch,
" Action: "
<< "Requesting,"
<< " URL: " << res.url.c_str() << " Size: "
<< (response.data != nullptr ? response.data->size() : 0) << "B,"
<< " Time")
}
callback(response);
});
};
// Initial tasksSize is used to check whether any of
// the sources were able to request a resource.
const std::size_t tasksSize = tasks.size();
// Waterfall resource request processing and return early once resource was requested.
if (assetFileSource && assetFileSource->canRequest(resource)) {
// Asset request
tasks[req] = assetFileSource->request(resource, callback);
} else if (localFileSource && localFileSource->canRequest(resource)) {
// Local file request
tasks[req] = localFileSource->request(resource, callback);
} else if (databaseFileSource && databaseFileSource->canRequest(resource)) {
// Try cache only request if needed.
if (resource.loadingMethod == Resource::LoadingMethod::CacheOnly) {
tasks[req] = databaseFileSource->request(resource, callback);
} else {
// Cache request with fallback to network with cache control
tasks[req] = databaseFileSource->request(resource, [=](Response response) {
Resource res = resource;
// Resource is in the cache
if (!response.noContent) {
if (response.isUsable()) {
callback(response);
// Set the priority of existing resource to low if it's expired but usable.
res.setPriority(Resource::Priority::Low);
}
// Copy response fields for cache control request
res.priorModified = response.modified;
res.priorExpires = response.expires;
res.priorEtag = response.etag;
res.priorData = response.data;
}
tasks[req] = requestFromNetwork(res, std::move(tasks[req]));
});
}
} else if (auto networkReq = requestFromNetwork(resource, nullptr)) {
// Get from the online file source
tasks[req] = std::move(networkReq);
}
// If no new tasks were added, notify client that request cannot be processed.
if (tasks.size() == tasksSize) {
Response response;
response.noContent = true;
response.error =
std::make_unique<Response::Error>(Response::Error::Reason::Other, "Unsupported resource request.");
callback(response);
}
}
void cancel(AsyncRequest* req) {
assert(req);
tasks.erase(req);
}
private:
const std::shared_ptr<FileSource> assetFileSource;
const std::shared_ptr<FileSource> databaseFileSource;
const std::shared_ptr<FileSource> localFileSource;
const std::shared_ptr<FileSource> onlineFileSource;
std::map<AsyncRequest*, std::unique_ptr<AsyncRequest>> tasks;
};
class MainResourceLoader::Impl {
public:
Impl(std::shared_ptr<FileSource> assetFileSource_,
std::shared_ptr<FileSource> databaseFileSource_,
std::shared_ptr<FileSource> localFileSource_,
std::shared_ptr<FileSource> onlineFileSource_)
: assetFileSource(std::move(assetFileSource_)),
databaseFileSource(std::move(databaseFileSource_)),
localFileSource(std::move(localFileSource_)),
onlineFileSource(std::move(onlineFileSource_)),
supportsCacheOnlyRequests_(bool(databaseFileSource)),
thread(std::make_unique<util::Thread<MainResourceLoaderThread>>(
util::makeThreadPrioritySetter(platform::EXPERIMENTAL_THREAD_PRIORITY_WORKER),
"ResourceLoaderThread",
assetFileSource,
databaseFileSource,
localFileSource,
onlineFileSource)) {}
std::unique_ptr<AsyncRequest> request(const Resource& resource, Callback callback) {
auto req = std::make_unique<FileSourceRequest>(std::move(callback));
req->onCancel([actorRef = thread->actor(), req = req.get()]() {
actorRef.invoke(&MainResourceLoaderThread::cancel, req);
});
thread->actor().invoke(&MainResourceLoaderThread::request, req.get(), resource, req->actor());
return std::move(req);
}
bool canRequest(const Resource& resource) const {
return (assetFileSource && assetFileSource->canRequest(resource)) ||
(localFileSource && localFileSource->canRequest(resource)) ||
(databaseFileSource && databaseFileSource->canRequest(resource)) ||
(onlineFileSource && onlineFileSource->canRequest(resource));
}
bool supportsCacheOnlyRequests() const { return supportsCacheOnlyRequests_; }
void pause() { thread->pause(); }
void resume() { thread->resume(); }
private:
const std::shared_ptr<FileSource> assetFileSource;
const std::shared_ptr<FileSource> databaseFileSource;
const std::shared_ptr<FileSource> localFileSource;
const std::shared_ptr<FileSource> onlineFileSource;
const bool supportsCacheOnlyRequests_;
const std::unique_ptr<util::Thread<MainResourceLoaderThread>> thread;
};
MainResourceLoader::MainResourceLoader(const ResourceOptions& options)
: impl(std::make_unique<Impl>(FileSourceManager::get()->getFileSource(FileSourceType::Asset, options),
FileSourceManager::get()->getFileSource(FileSourceType::Database, options),
FileSourceManager::get()->getFileSource(FileSourceType::FileSystem, options),
FileSourceManager::get()->getFileSource(FileSourceType::Network, options))) {}
MainResourceLoader::~MainResourceLoader() = default;
bool MainResourceLoader::supportsCacheOnlyRequests() const {
return impl->supportsCacheOnlyRequests();
}
std::unique_ptr<AsyncRequest> MainResourceLoader::request(const Resource& resource, Callback callback) {
return impl->request(resource, std::move(callback));
}
bool MainResourceLoader::canRequest(const Resource& resource) const {
return impl->canRequest(resource);
}
void MainResourceLoader::pause() {
impl->pause();
}
void MainResourceLoader::resume() {
impl->resume();
}
} // namespace mbgl
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