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/*
Copyright (C) 2008- The University of Notre Dame
This software is distributed under the GNU General Public License.
See the file COPYING for details.
*/
#ifndef PROCESS_H
#define PROCESS_H
#include <sys/time.h>
#include <sys/types.h>
#include <sys/resource.h>
#include <sys/wait.h>
/** @file process.h
Provides a higher level interface to finding information about complete processes.
Useful as a replacement for <tt>wait</tt>, <tt>waitpid</tt> and similar calls,
which do not allow the caller to check for completion without permanently removing
the completion notice.
<p>
Call @ref process_pending to see if there is a recently completed process,
@ref process_wait to wait for completion with a timeout, and @ref process_putback
to put the completion back into the queue.
*/
/** Describes a completed process.
Each element of this structure is the same as returned by Unix wait4().
@see process_wait
*/
struct process_info {
pid_t pid; /**< The process ID of a complete process. */
int status; /**< The exit status of the process. */
struct rusage rusage; /**< The resource usage of the process. */
};
/** Wait for a process to complete, and return its status.
Wait for up to timeout seconds for a child process to complete.
If a process has completed, its status will be returned in a @ref process_info
structure. The caller may either call <tt>free</tt> to release the structure,
or may return it via @ref process_putback in order to allow another caller to retrieve it.
@param timeout The time, in seconds to wait for a child to complete. If zero, do not wait at all.
@return A @ref process_info structure describing the child process status, or null if no
process completed in the available time.
*/
struct process_info *process_wait(int timeout);
/** Wait for a specific process to complete and return its status.
Like @ref process_wait, but waits for a specific pid.
*/
struct process_info *process_waitpid(pid_t pid, int timeout);
/** Detect if a child process has completed.
If so, its status may be obtained without delay by calling @ref process_wait .
@return True if a child process has completed.
*/
int process_pending();
/** Return a process_info structure to the queue.
@param p A @ref process_info structure returned by @ref process_wait.
*/
void process_putback(struct process_info *p);
#endif
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