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Diffstat (limited to 'include/ap_mpm.h')
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1 files changed, 235 insertions, 0 deletions
diff --git a/include/ap_mpm.h b/include/ap_mpm.h new file mode 100644 index 0000000..71f8f47 --- /dev/null +++ b/include/ap_mpm.h @@ -0,0 +1,235 @@ +/* Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +/** + * @file ap_mpm.h + * @brief Apache Multi-Processing Module library + * + * @defgroup APACHE_CORE_MPM Multi-Processing Module library + * @ingroup APACHE_CORE + * @{ + */ + +#ifndef AP_MPM_H +#define AP_MPM_H + +#include "apr_thread_proc.h" +#include "httpd.h" +#include "scoreboard.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/* + The MPM, "multi-processing model" provides an abstraction of the + interface with the OS for distributing incoming connections to + threads/process for processing. http_main invokes the MPM, and + the MPM runs until a shutdown/restart has been indicated. + The MPM calls out to the apache core via the ap_process_connection + function when a connection arrives. + + The MPM may or may not be multithreaded. In the event that it is + multithreaded, at any instant it guarantees a 1:1 mapping of threads + ap_process_connection invocations. + + Note: In the future it will be possible for ap_process_connection + to return to the MPM prior to finishing the entire connection; and + the MPM will proceed with asynchronous handling for the connection; + in the future the MPM may call ap_process_connection again -- but + does not guarantee it will occur on the same thread as the first call. + + The MPM further guarantees that no asynchronous behaviour such as + longjmps and signals will interfere with the user code that is + invoked through ap_process_connection. The MPM may reserve some + signals for its use (i.e. SIGUSR1), but guarantees that these signals + are ignored when executing outside the MPM code itself. (This + allows broken user code that does not handle EINTR to function + properly.) + + The suggested server restart and stop behaviour will be "graceful". + However the MPM may choose to terminate processes when the user + requests a non-graceful restart/stop. When this occurs, the MPM kills + all threads with extreme prejudice, and destroys the pchild pool. + User cleanups registered in the pchild apr_pool_t will be invoked at + this point. (This can pose some complications, the user cleanups + are asynchronous behaviour not unlike longjmp/signal... but if the + admin is asking for a non-graceful shutdown, how much effort should + we put into doing it in a nice way?) + + unix/posix notes: + - The MPM does not set a SIGALRM handler, user code may use SIGALRM. + But the preferred method of handling timeouts is to use the + timeouts provided by the BUFF abstraction. + - The proper setting for SIGPIPE is SIG_IGN, if user code changes it + for any of their own processing, it must be restored to SIG_IGN + prior to executing or returning to any apache code. + TODO: add SIGPIPE debugging check somewhere to make sure it's SIG_IGN +*/ + +/** + * Pass control to the MPM for steady-state processing. It is responsible + * for controlling the parent and child processes. It will run until a + * restart/shutdown is indicated. + * @param pconf the configuration pool, reset before the config file is read + * @param plog the log pool, reset after the config file is read + * @param server_conf the global server config. + * @return DONE for shutdown OK otherwise. + */ +AP_DECLARE_HOOK(int, mpm, (apr_pool_t *pconf, apr_pool_t *plog, server_rec *server_conf)) + +/** + * Spawn a process with privileges that another module has requested + * @param r The request_rec of the current request + * @param newproc The resulting process handle. + * @param progname The program to run + * @param args the arguments to pass to the new program. The first + * one should be the program name. + * @param env The new environment apr_table_t for the new process. This + * should be a list of NULL-terminated strings. + * @param attr the procattr we should use to determine how to create the new + * process + * @param p The pool to use. + */ +AP_DECLARE(apr_status_t) ap_os_create_privileged_process( + const request_rec *r, + apr_proc_t *newproc, + const char *progname, + const char * const *args, + const char * const *env, + apr_procattr_t *attr, + apr_pool_t *p); + +/* Subtypes/Values for AP_MPMQ_IS_THREADED and AP_MPMQ_IS_FORKED */ +#define AP_MPMQ_NOT_SUPPORTED 0 /* This value specifies that an */ + /* MPM is not capable of */ + /* threading or forking. */ +#define AP_MPMQ_STATIC 1 /* This value specifies that */ + /* an MPM is using a static */ + /* number of threads or daemons */ +#define AP_MPMQ_DYNAMIC 2 /* This value specifies that */ + /* an MPM is using a dynamic */ + /* number of threads or daemons */ + +/* Values returned for AP_MPMQ_MPM_STATE */ +#define AP_MPMQ_STARTING 0 +#define AP_MPMQ_RUNNING 1 +#define AP_MPMQ_STOPPING 2 + +#define AP_MPMQ_MAX_DAEMON_USED 1 /* Max # of daemons used so far */ +#define AP_MPMQ_IS_THREADED 2 /* MPM can do threading */ +#define AP_MPMQ_IS_FORKED 3 /* MPM can do forking */ +#define AP_MPMQ_HARD_LIMIT_DAEMONS 4 /* The compiled max # daemons */ +#define AP_MPMQ_HARD_LIMIT_THREADS 5 /* The compiled max # threads */ +#define AP_MPMQ_MAX_THREADS 6 /* # of threads/child by config */ +#define AP_MPMQ_MIN_SPARE_DAEMONS 7 /* Min # of spare daemons */ +#define AP_MPMQ_MIN_SPARE_THREADS 8 /* Min # of spare threads */ +#define AP_MPMQ_MAX_SPARE_DAEMONS 9 /* Max # of spare daemons */ +#define AP_MPMQ_MAX_SPARE_THREADS 10 /* Max # of spare threads */ +#define AP_MPMQ_MAX_REQUESTS_DAEMON 11 /* Max # of requests per daemon */ +#define AP_MPMQ_MAX_DAEMONS 12 /* Max # of daemons by config */ +#define AP_MPMQ_MPM_STATE 13 /* starting, running, stopping */ +#define AP_MPMQ_IS_ASYNC 14 /* MPM can process async connections */ +#define AP_MPMQ_GENERATION 15 /* MPM generation */ +#define AP_MPMQ_HAS_SERF 16 /* MPM can drive serf internally */ + +/** + * Query a property of the current MPM. + * @param query_code One of APM_MPMQ_* + * @param result A location to place the result of the query + * @return APR_EGENERAL if an mpm-query hook has not been registered; + * APR_SUCCESS or APR_ENOTIMPL otherwise + * @remark The MPM doesn't register the implementing hook until the + * register_hooks hook is called, so modules cannot use ap_mpm_query() + * until after that point. + * @fn int ap_mpm_query(int query_code, int *result) + */ +AP_DECLARE(apr_status_t) ap_mpm_query(int query_code, int *result); + + +typedef void (ap_mpm_callback_fn_t)(void *baton); + +/* only added support in the Event MPM.... check for APR_ENOTIMPL */ +AP_DECLARE(apr_status_t) ap_mpm_register_timed_callback(apr_time_t t, + ap_mpm_callback_fn_t *cbfn, + void *baton); + +typedef enum mpm_child_status { + MPM_CHILD_STARTED, + MPM_CHILD_EXITED, + MPM_CHILD_LOST_SLOT +} mpm_child_status; + +/** + * Allow a module to remain aware of MPM child process state changes, + * along with the generation and scoreboard slot of the process changing + * state. + * + * With some MPMs (event and worker), an active MPM child process may lose + * its scoreboard slot if the child process is exiting and the scoreboard + * slot is needed by other processes. When this occurs, the hook will be + * called with the MPM_CHILD_LOST_SLOT state. + * + * @param s The main server_rec. + * @param pid The id of the MPM child process. + * @param gen The server generation of that child process. + * @param slot The scoreboard slot number, or -1. It will be -1 when an + * MPM child process exits, and that child had previously lost its + * scoreboard slot. + * @param state One of the mpm_child_status values. Modules should ignore + * unrecognized values. + */ +AP_DECLARE_HOOK(void,child_status,(server_rec *s, pid_t pid, ap_generation_t gen, + int slot, mpm_child_status state)) + +/** + * Allow a module to be notified when the last child process of a generation + * exits. + * + * @param s The main server_rec. + * @param gen The server generation which is now completely finished. + */ +AP_DECLARE_HOOK(void,end_generation,(server_rec *s, ap_generation_t gen)) + +/* Defining GPROF when compiling uses the moncontrol() function to + * disable gprof profiling in the parent, and enable it only for + * request processing in children (or in one_process mode). It's + * absolutely required to get useful gprof results under linux + * because the profile itimers and such are disabled across a + * fork(). It's probably useful elsewhere as well. + */ +#ifdef GPROF +extern void moncontrol(int); +#define AP_MONCONTROL(x) moncontrol(x) +#else +#define AP_MONCONTROL(x) +#endif + +#ifdef AP_ENABLE_EXCEPTION_HOOK +typedef struct ap_exception_info_t { + int sig; + pid_t pid; +} ap_exception_info_t; + +AP_DECLARE_HOOK(int,fatal_exception,(ap_exception_info_t *ei)) +#endif /*AP_ENABLE_EXCEPTION_HOOK*/ + +#ifdef __cplusplus +} +#endif + +#endif +/** @} */ |