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AIOContextPool: type aliases for clarity, commentary corrections [#METR-18618]

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This commit is contained in:
Andrey Mironov 2015-11-05 17:11:09 +03:00
parent 249a5922fe
commit ad27ad476d
1 changed files with 12 additions and 8 deletions
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20
dbms/include/DB/Common/AIO.h
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@ -66,15 +66,18 @@ class AIOContextPool : public Singleton<AIOContextPool>
friend class Singleton<AIOContextPool>; friend class Singleton<AIOContextPool>;
static const auto max_concurrent_events = 128; static const auto max_concurrent_events = 128;
static const auto max_timeout_sec = 1; static const auto timeout_sec = 1;
static const auto max_timeout_nsec = 0;
AIOContext aio_context{max_concurrent_events}; AIOContext aio_context{max_concurrent_events};
std::size_t id{}; using id_t = size_t;
using bytes_read_t = ssize_t;
/// Autoincremental id used to identify completed requests
id_t id{};
mutable std::mutex mutex; mutable std::mutex mutex;
mutable std::condition_variable have_resources; mutable std::condition_variable have_resources;
std::map<std::size_t, std::promise<ssize_t>> promises; std::map<id_t, std::promise<bytes_read_t>> promises;
std::atomic<bool> cancelled{false}; std::atomic<bool> cancelled{false};
std::thread io_completion_monitor{&AIOContextPool::monitorForCompletion, this}; std::thread io_completion_monitor{&AIOContextPool::monitorForCompletion, this};
@ -110,11 +113,11 @@ class AIOContextPool : public Singleton<AIOContextPool>
int getCompletionEvents(io_event events[], const int max_events) int getCompletionEvents(io_event events[], const int max_events)
{ {
timespec timeout{max_timeout_sec, max_timeout_nsec}; timespec timeout{timeout_sec};
auto num_events = 0; auto num_events = 0;
/// request 1 to `max_concurrent_events` events /// request 1 to `max_events` events
while ((num_events = io_getevents(aio_context.ctx, 1, max_events, events, &timeout)) < 0) while ((num_events = io_getevents(aio_context.ctx, 1, max_events, events, &timeout)) < 0)
if (errno != EINTR) if (errno != EINTR)
throwFromErrno("io_getevents: Failed to wait for asynchronous IO completion", throwFromErrno("io_getevents: Failed to wait for asynchronous IO completion",
@ -160,7 +163,8 @@ class AIOContextPool : public Singleton<AIOContextPool>
} }
public: public:
std::future<ssize_t> post(struct iocb & iocb) /// Request AIO read operation for iocb, returns a future with number of bytes read
std::future<bytes_read_t> post(struct iocb & iocb)
{ {
std::unique_lock<std::mutex> lock{mutex}; std::unique_lock<std::mutex> lock{mutex};
@ -168,7 +172,7 @@ public:
const auto request_id = id++; const auto request_id = id++;
/// create a promise and put request in "queue" /// create a promise and put request in "queue"
promises.emplace(request_id, std::promise<ssize_t>{}); promises.emplace(request_id, std::promise<bytes_read_t>{});
/// store id in AIO request for further identification /// store id in AIO request for further identification
iocb.aio_data = request_id; iocb.aio_data = request_id;