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// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "platform/impl/socket_handle_waiter.h"
#include <algorithm>
#include <atomic>
#include "absl/algorithm/container.h"
#include "util/osp_logging.h"
namespace openscreen {
SocketHandleWaiter::SocketHandleWaiter(ClockNowFunctionPtr now_function)
: now_function_(now_function) {}
void SocketHandleWaiter::Subscribe(Subscriber* subscriber,
SocketHandleRef handle) {
std::lock_guard<std::mutex> lock(mutex_);
if (handle_mappings_.find(handle) == handle_mappings_.end()) {
handle_mappings_.emplace(handle, SocketSubscription{subscriber});
}
}
void SocketHandleWaiter::Unsubscribe(Subscriber* subscriber,
SocketHandleRef handle) {
std::lock_guard<std::mutex> lock(mutex_);
auto iterator = handle_mappings_.find(handle);
if (handle_mappings_.find(handle) != handle_mappings_.end()) {
handle_mappings_.erase(iterator);
}
}
void SocketHandleWaiter::UnsubscribeAll(Subscriber* subscriber) {
std::lock_guard<std::mutex> lock(mutex_);
for (auto it = handle_mappings_.begin(); it != handle_mappings_.end();) {
if (it->second.subscriber == subscriber) {
it = handle_mappings_.erase(it);
} else {
it++;
}
}
}
void SocketHandleWaiter::OnHandleDeletion(Subscriber* subscriber,
SocketHandleRef handle,
bool disable_locking_for_testing) {
std::unique_lock<std::mutex> lock(mutex_);
auto it = handle_mappings_.find(handle);
if (it != handle_mappings_.end()) {
handle_mappings_.erase(it);
if (!disable_locking_for_testing) {
handles_being_deleted_.push_back(handle);
OSP_DVLOG << "Starting to block for handle deletion";
// This code will allow us to block completion of the socket destructor
// (and subsequent invalidation of pointers to this socket) until we no
// longer are waiting on a SELECT(...) call to it, since we only signal
// this condition variable's wait(...) to proceed outside of SELECT(...).
handle_deletion_block_.wait(lock, [this, handle]() {
return std::find(handles_being_deleted_.begin(),
handles_being_deleted_.end(),
handle) == handles_being_deleted_.end();
});
OSP_DVLOG << "\tDone blocking for handle deletion!";
}
}
}
void SocketHandleWaiter::ProcessReadyHandles(
std::vector<HandleWithSubscription>* handles,
Clock::duration timeout) {
if (handles->empty()) {
return;
}
Clock::time_point start_time = now_function_();
// Process the stalest handles one by one until we hit our timeout.
do {
Clock::time_point oldest_time = Clock::time_point::max();
HandleWithSubscription& oldest_handle = handles->at(0);
for (HandleWithSubscription& handle : *handles) {
// Skip already processed handles.
if (handle.subscription->last_updated >= start_time) {
continue;
}
// Select the oldest handle.
if (handle.subscription->last_updated < oldest_time) {
oldest_time = handle.subscription->last_updated;
oldest_handle = handle;
}
}
// Already processed all handles.
if (oldest_time == Clock::time_point::max()) {
return;
}
// Process the oldest handle.
oldest_handle.subscription->last_updated = now_function_();
oldest_handle.subscription->subscriber->ProcessReadyHandle(
oldest_handle.ready_handle.handle, oldest_handle.ready_handle.flags);
} while (now_function_() - start_time <= timeout);
}
Error SocketHandleWaiter::ProcessHandles(Clock::duration timeout) {
Clock::time_point start_time = now_function_();
std::vector<SocketHandleRef> handles;
{
std::lock_guard<std::mutex> lock(mutex_);
handles_being_deleted_.clear();
handle_deletion_block_.notify_all();
handles.reserve(handle_mappings_.size());
for (const auto& pair : handle_mappings_) {
handles.push_back(pair.first);
}
}
Clock::time_point current_time = now_function_();
Clock::duration remaining_timeout = timeout - (current_time - start_time);
ErrorOr<std::vector<ReadyHandle>> changed_handles =
AwaitSocketsReadable(handles, remaining_timeout);
std::vector<HandleWithSubscription> ready_handles;
{
std::lock_guard<std::mutex> lock(mutex_);
handles_being_deleted_.clear();
handle_deletion_block_.notify_all();
if (changed_handles) {
auto& ch = changed_handles.value();
ready_handles.reserve(ch.size());
for (const auto& handle : ch) {
auto mapping_it = handle_mappings_.find(handle.handle);
if (mapping_it != handle_mappings_.end()) {
ready_handles.push_back(
HandleWithSubscription{handle, &(mapping_it->second)});
}
}
}
if (changed_handles.is_error()) {
return changed_handles.error();
}
current_time = now_function_();
remaining_timeout = timeout - (current_time - start_time);
ProcessReadyHandles(&ready_handles, remaining_timeout);
}
return Error::None();
}
} // namespace openscreen
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