PyFCGI/include/pyworker.h

/*
 * Copyright (C) 2019 Weber Yann
 * 
 * This file is part of PyFCGI.
 * 
 * PyFCGI is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 * 
 * PyFCGI is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with PyFCGI.  If not, see <http://www.gnu.org/licenses/>.
 */
/**@defgroup worker_process Worker processes
 * @brief Processus handling python execution with @ref work() function
 *
 * This kind of process are @ref spawn() by a @ref work_master_proc
 * @section Running Python
 * Running embed python in FCGI mean serving multiple requests with a single
 * python process, meaning :
 * - environnement variable of the living Python process need to be updated
 * - we need a way to communicate with python code
 *
 * @subsection worker_proc_ipc Communicating with python
 * sys.stdout & sys.stderr will be used to communicate in python. Shortly 
 * after python initialize @ref update_python_fd() update these two file
 * objects with freshly created pipes.
 *
 * @subsubsection worker_proc_ipc_piper The piper process
 *
 * When a request arrive, the worker process fork again in a @ref worker_piper() child
 * process that will read the two pipes. Sending stdout to FCGI using printf
 * and stderr to syslog.
 *
 * @subsection worker_proc_environ Updating os.environ
 * os.environ is a special kind of dictionnary, automatically calling 
 * os.putenv() function. This function will attempt (and succeed) to update
 * the real process environnement, making a nasty conflict with libfcgi (trying
 * to free an environnement it did not create anymore...).
 *
 * The os.environ is replaced by a simple python dict by @ref update_pyenv()
 * once a request.
 *
 * @see update_python_path()
 *
 * @ingroup work_master_proc
 */
/**@file pyworker.h
 * @ingroup worker_process
 */
#ifndef _PYWORKER__H___
#define _PYWORKER__H___

#include "config.h"

#include <fcgiapp.h>
#include <fcgi_stdio.h> /* fcgi library; put it first*/

#define PY_SSIZE_T_CLEAN
#include <Python.h>


#include <unistd.h>
#include <fcntl.h>
#include <syslog.h>
#include <signal.h>
#include <limits.h>
#include <poll.h>
#include <sched.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/wait.h>

#include "logger.h"
#include "pyutils.h"
#include "python_pyfcgi.h"

#define WPIPER_SIG 30
#define PIPER_STACK_SZ (1024 * 1024 * 4)

//extern char **environ;

typedef unsigned long int pywrkid_t;
typedef struct piper_args_s piper_args_t;

struct piper_args_s
{
	int wrk_id, pystdout, pystderr, ctl_pipe;
	//int req_id;
	FCGX_Stream *out;
	struct sigaction *act;
};

extern PyObject* response_status;
extern PyObject* response_headers;

/**@brief The function that initialize the alternate python worker
 * @ingroup worker_process
 *
 * This function handles python worker by running a PEP333 application function.
 * The start_response() function set @ref response_status and
 * @ref response_headers globals.
 * @param wrk_id worker id
 * @return 0 if exit avec max requests
 */
int work333(int wrk_id);

/**@brief the function that initialize the alternate python worker
 * @ingroup worker_process
 *
 * This function handles python worker using stdout to communicate with
 * FCGI. This function clones for each request, running worker_piper()
 * @param wrk_id worker id
 * @return 0 if exit avec max requests
 */
int work(int wrk_id);

/*/**@brief function for a subprocess designed to read stdin & stdout from
 * python & forward them to syslog or FCGI
 * @ingroup worker_process
 * @param int worker id
 * @param int request id
 * @param int pystdout
 * @param int pystderr
 * @param int ctlpipe a pipe closed when the process is ready
 * @note Exit after signal sent by parent & when poll indicate the pipes are
 * empty
 */
/*
void worker_piper(int, int, int, int, int, FCGX_Stream*);
*/
int worker_piper(void*);

/**@brief worker piper sigaction handler
 */
void worker_piper_sighandler(int);

/**@brief empty pipes and log content for pep333 workers
 * @todo enhance logging : 1 lines per logline + line counter ?
 * @todo sys.stdout & sys.stderr can have an implementation like
 * libpyfcgi.IoIn to avoir useless buffering
 * @param pipe_std pipe for stdout
 * @param pipe_err pipe for stderr
 * @param flush python flush methods 
 */
void worker_log_pipes(int pipe_std, int pipe_err, PyObject* flush[2]);

/**@brief Attempt to read the request size from ctl pipe
 * @param ctl_pipe read fd
 * @param rep_sz response size
 * @return 0 if no error
 */
int ctl_get_rep_sz(int ctl_pipe, size_t* rep_sz);

void worker_sighandler(int);
void worker_sigalrmhandler(int signum);

#endif