// Copyright 2018 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_MESSAGE_LOOP_WATCHABLE_IO_MESSAGE_PUMP_POSIX_H_
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#define BASE_MESSAGE_LOOP_WATCHABLE_IO_MESSAGE_PUMP_POSIX_H_
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#include "base/location.h"
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#include "base/macros.h"
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namespace base {
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class WatchableIOMessagePumpPosix {
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public:
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// Used with WatchFileDescriptor to asynchronously monitor the I/O readiness
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// of a file descriptor.
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class FdWatcher {
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public:
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virtual void OnFileCanReadWithoutBlocking(int fd) = 0;
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virtual void OnFileCanWriteWithoutBlocking(int fd) = 0;
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protected:
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virtual ~FdWatcher() = default;
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};
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class FdWatchControllerInterface {
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public:
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explicit FdWatchControllerInterface(const Location& from_here);
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// Subclasses must call StopWatchingFileDescriptor() in their destructor
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// (this parent class cannot generically do it for them as it must usually
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// be invoked before they destroy their state which happens before the
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// parent destructor is invoked).
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virtual ~FdWatchControllerInterface();
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// NOTE: This method isn't called StopWatching() to avoid confusion with the
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// win32 ObjectWatcher class. While this doesn't really need to be virtual
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// as there's only one impl per platform and users don't use pointers to the
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// base class. Having this interface forces implementers to share similar
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// implementations (a problem in the past).
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// Stop watching the FD, always safe to call. No-op if there's nothing to
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// do.
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virtual bool StopWatchingFileDescriptor() = 0;
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const Location& created_from_location() const {
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return created_from_location_;
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}
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private:
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const Location created_from_location_;
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DISALLOW_COPY_AND_ASSIGN(FdWatchControllerInterface);
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};
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enum Mode {
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WATCH_READ = 1 << 0,
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WATCH_WRITE = 1 << 1,
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WATCH_READ_WRITE = WATCH_READ | WATCH_WRITE
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};
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// Every subclass of WatchableIOMessagePumpPosix must provide a
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// WatchFileDescriptor() which has the following signature where
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// |FdWatchController| must be the complete type based on
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// FdWatchControllerInterface.
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// Registers |delegate| with the current thread's message loop so that its
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// methods are invoked when file descriptor |fd| becomes ready for reading or
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// writing (or both) without blocking. |mode| selects ready for reading, for
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// writing, or both. See "enum Mode" above. |controller| manages the
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// lifetime of registrations. ("Registrations" are also ambiguously called
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// "events" in many places, for instance in libevent.) It is an error to use
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// the same |controller| for different file descriptors; however, the same
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// controller can be reused to add registrations with a different |mode|. If
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// |controller| is already attached to one or more registrations, the new
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// registration is added onto those. If an error occurs while calling this
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// method, any registration previously attached to |controller| is removed.
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// Returns true on success. Must be called on the same thread the MessagePump
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// is running on.
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// bool WatchFileDescriptor(int fd,
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// bool persistent,
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// int mode,
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// FdWatchController* controller,
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// FdWatcher* delegate) = 0;
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};
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} // namespace base
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#endif // BASE_MESSAGE_LOOP_WATCHABLE_IO_MESSAGE_PUMP_POSIX_H_
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