mirror of
https://github.com/fish-shell/fish-shell
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106 lines
3.4 KiB
C++
106 lines
3.4 KiB
C++
#ifndef FISH_FD_MONITOR_H
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#define FISH_FD_MONITOR_H
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#include <chrono>
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#include <cstdint>
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#include <functional>
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// Needed for musl
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#include <sys/select.h> // IWYU pragma: keep
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#include "common.h"
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#include "maybe.h"
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class fd_monitor_t;
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/// An item containing an fd and callback, which can be monitored to watch when it becomes readable,
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/// and invoke the callback.
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struct fd_monitor_item_t {
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friend class fd_monitor_t;
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/// The callback type for the item.
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/// It will be invoked when either \p fd is readable, or if the timeout was hit.
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using callback_t = std::function<void(autoclose_fd_t &fd, bool timed_out)>;
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/// A sentinel value meaning no timeout.
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static constexpr uint64_t kNoTimeout = std::numeric_limits<uint64_t>::max();
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/// The fd to monitor.
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autoclose_fd_t fd{};
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/// A callback to be invoked when the fd is readable, or when we are timed out.
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/// If we time out, then timed_out will be true.
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/// If the fd is invalid on return from the function, then the item is removed.
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callback_t callback{};
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/// The timeout in microseconds, or kNoTimeout for none.
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/// 0 timeouts are unsupported.
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uint64_t timeout_usec{kNoTimeout};
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/// Construct from a file, callback, and optional timeout.
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fd_monitor_item_t(autoclose_fd_t fd, callback_t callback, uint64_t timeout_usec = kNoTimeout)
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: fd(std::move(fd)), callback(std::move(callback)), timeout_usec(timeout_usec) {
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assert(timeout_usec > 0 && "Invalid timeout");
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}
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fd_monitor_item_t() = default;
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private:
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// Fields and methods for the private use of fd_monitor_t.
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using time_point_t = std::chrono::time_point<std::chrono::steady_clock>;
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// The last time we were called, or the initialization point.
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maybe_t<time_point_t> last_time{};
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// \return the number of microseconds until the timeout should trigger, or kNoTimeout for none.
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// A 0 return means we are at or past the timeout.
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uint64_t usec_remaining(const time_point_t &now) const;
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// Invoke this item's callback if its value is set in fd or has timed out.
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// \return true to retain the item, false to remove it.
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bool service_item(const fd_set *fds, const time_point_t &now);
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};
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/// A class which can monitor a set of fds, invoking a callback when any becomes readable, or when
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/// per-item-configurable timeouts are hit.
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class fd_monitor_t {
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public:
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using item_list_t = std::vector<fd_monitor_item_t>;
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fd_monitor_t();
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~fd_monitor_t();
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/// Add an item to monitor.
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void add(fd_monitor_item_t &&item);
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private:
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// The background thread runner.
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void run_in_background();
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// Add a pending item, marking the thread as running.
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// \return true if we should start the thread.
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bool add_pending_get_start_thread(fd_monitor_item_t &&item);
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// The list of items to monitor. This is only accessed on the background thread.
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item_list_t items_{};
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// Set to true by the background thread when our self-pipe becomes readable.
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bool has_pending_{false};
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// Latched to true by the background thread if our self-pipe is closed, which indicates we are
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// in the destructor and so should terminate.
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bool terminate_{false};
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struct data_t {
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/// Pending items.
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item_list_t pending{};
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/// Whether the thread is running.
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bool running{false};
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};
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owning_lock<data_t> data_;
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/// The write end of our self-pipe.
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autoclose_fd_t notify_write_fd_{};
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};
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#endif
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