diff options
author | Sean Bright <sean.bright@gmail.com> | 2017-04-17 20:06:10 -0400 |
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committer | Sean Bright <sean.bright@gmail.com> | 2017-04-24 12:46:27 -0400 |
commit | cea3742c549a3c31621d2d29a1b78b42211e01d0 (patch) | |
tree | 10d3b39a433741922041fdbe0608d22e1905f1f9 /include/asterisk/alertpipe.h | |
parent | dac4442cdd787b58035fcd13d51abbf50a4d7cb3 (diff) |
core: Use eventfd for alert pipes on Linux when possible
The primary win of switching to eventfd when possible is that it only
uses a single file descriptor while pipe() will use two. This means for
each bridge channel we're reducing the number of required file
descriptors by 1, and - if you're using timerfd - we also now have 1
less file descriptor per Asterisk channel.
The API is not ideal (passing int arrays), but this is the cleanest
approach I could come up with to maintain API/ABI.
I've also removed what I believe to be an erroneous code block that
checked the non-blocking flag on the pipe ends for each read. If the
file descriptor is 'losing' its non-blocking mode, it is because of a
bug somewhere else in our code.
In my testing I haven't seen any measurable difference in performance.
Change-Id: Iff0fb1573e7f7a187d5211ddc60aa8f3da3edb1d
Diffstat (limited to 'include/asterisk/alertpipe.h')
-rw-r--r-- | include/asterisk/alertpipe.h | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/include/asterisk/alertpipe.h b/include/asterisk/alertpipe.h new file mode 100644 index 000000000..5ff854ce8 --- /dev/null +++ b/include/asterisk/alertpipe.h @@ -0,0 +1,159 @@ +/* + * Asterisk -- An open source telephony toolkit. + * + * Copyright (C) 2017, Sean Bright + * + * Sean Bright <sean.bright@gmail.com> + * + * See http://www.asterisk.org for more information about + * the Asterisk project. Please do not directly contact + * any of the maintainers of this project for assistance; + * the project provides a web site, mailing lists and IRC + * channels for your use. + * + * This program is free software, distributed under the terms of + * the GNU General Public License Version 2. See the LICENSE file + * at the top of the source tree. + */ + +#ifndef ASTERISK_ALERTPIPE_H +#define ASTERISK_ALERTPIPE_H + +#include "asterisk/utils.h" + +typedef enum { + AST_ALERT_READ_SUCCESS = 0, + AST_ALERT_NOT_READABLE, + AST_ALERT_READ_FAIL, + AST_ALERT_READ_FATAL, +} ast_alert_status_t; + +/*! + * \brief Initialize an alert pipe + * \since 13.16.0 + * + * \param p a two-element array to hold the alert pipe's file descriptors + * + * \return non-zero if a failure occurred, zero otherwise. + */ +int ast_alertpipe_init(int alert_pipe[2]); + +/*! + * \brief Close an alert pipe + * \since 13.16.0 + * + * \param p a two-element containing the alert pipe's file descriptors + */ +void ast_alertpipe_close(int alert_pipe[2]); + +/*! + * \brief Read an event from an alert pipe + * \since 13.16.0 + * + * \param p a two-element array containing the alert pipe's file descriptors + * + * \retval AST_ALERT_READ_SUCCESS on success + * \retval AST_ALERT_NOT_READABLE if the alert pipe is not readable + * \retval AST_ALERT_READ_FATAL if the alert pipe's file descriptors are in + * blocking mode, or a read error occurs. + */ +ast_alert_status_t ast_alertpipe_read(int alert_pipe[2]); + +/*! + * \brief Write an event to an alert pipe + * \since 13.16.0 + * + * \param p a two-element array containing the alert pipe's file descriptors + * + * \return see write(2) + */ +ssize_t ast_alertpipe_write(int alert_pipe[2]); + +/*! + * \brief Consume all alerts written to the alert pipe + * \since 13.16.0 + * + * \param p a two-element array containing the alert pipe's file descriptors + * + * \retval AST_ALERT_READ_SUCCESS on success + * \retval AST_ALERT_NOT_READABLE if the alert pipe is not readable + * \retval AST_ALERT_READ_FATAL if the alert pipe's file descriptors are in + * blocking mode, or a read error occurs. + */ +ast_alert_status_t ast_alertpipe_flush(int alert_pipe[2]); + +/*! + * \brief Sets the alert pipe file descriptors to default values + * \since 13.16.0 + * + * \param p a two-element array containing the alert pipe's file descriptors + */ +AST_INLINE_API( +void ast_alertpipe_clear(int alert_pipe[2]), +{ + alert_pipe[0] = alert_pipe[1] = -1; +} +) + +/*! + * \brief Determine if the alert pipe is readable + * \since 13.16.0 + * + * \param p a two-element array containing the alert pipe's file descriptors + * + * \return non-zero if the alert pipe is readable, zero otherwise. + */ +AST_INLINE_API( +int attribute_pure ast_alertpipe_readable(int alert_pipe[2]), +{ + return alert_pipe[0] > -1; +} +) + +/*! + * \brief Determine if the alert pipe is writable + * \since 13.16.0 + * + * \param p a two-element array containing the alert pipe's file descriptors + * + * \return non-zero if the alert pipe is writable, zero otherwise. + */ +AST_INLINE_API( +int attribute_pure ast_alertpipe_writable(int alert_pipe[2]), +{ + return alert_pipe[1] > -1; +} +) + +/*! + * \brief Get the alert pipe's read file descriptor + * \since 13.16.0 + * + * \param p a two-element array containing the alert pipe's file descriptors + * + * \return -1 if the file descriptor is not initialized, a non-negative value + * otherwise. + */ +AST_INLINE_API( +int attribute_pure ast_alertpipe_readfd(int alert_pipe[2]), +{ + return alert_pipe[0]; +} +) + +/*! + * \brief Swap the file descriptors from two alert pipes + * \since 13.16.0 + * + * \param p1 a two-element array containing an alert pipe's file descriptors + * \param p2 a two-element array containing an alert pipe's file descriptors + */ +AST_INLINE_API( +void ast_alertpipe_swap(int alert_pipe_1[2], int alert_pipe_2[2]), +{ + SWAP(alert_pipe_1[0], alert_pipe_2[0]); + SWAP(alert_pipe_1[1], alert_pipe_2[1]); +} +) + +#endif /* ASTERISK_ALERTPIPE_H */ |