/* Copyright 2000-2005 The Apache Software Foundation or its licensors, as
 * applicable.
 *
 * Licensed 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.
 */

#ifndef APR_THREAD_PROC_H
#define APR_THREAD_PROC_H

/**
 * @file apr_thread_proc.h
 * @brief APR Thread and Process Library
 */

#include "apr.h"
#include "apr_file_io.h"
#include "apr_pools.h"
#include "apr_errno.h"

#if APR_HAVE_STRUCT_RLIMIT
#include <sys/time.h>
#include <sys/resource.h>
#endif

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

/**
 * @defgroup apr_thread_proc Threads and Process Functions
 * @ingroup APR 
 * @{
 */

typedef enum {
    APR_SHELLCMD,       /**< use the shell to invoke the program */
    APR_PROGRAM,        /**< invoke the program directly, no copied env */
    APR_PROGRAM_ENV,    /**< invoke the program, replicating our environment */
    APR_PROGRAM_PATH,   /**< find program on PATH, use our environment */
    APR_SHELLCMD_ENV    /**< use the shell to invoke the program,
                          *   replicating our environment
                          */
} apr_cmdtype_e;

typedef enum {
    APR_WAIT,           /**< wait for the specified process to finish */
    APR_NOWAIT          /**< do not wait -- just see if it has finished */
} apr_wait_how_e;

/* I am specifically calling out the values so that the macros below make
 * more sense.  Yes, I know I don't need to, but I am hoping this makes what
 * I am doing more clear.  If you want to add more reasons to exit, continue
 * to use bitmasks.
 */
typedef enum {
    APR_PROC_EXIT = 1,          /**< process exited normally */
    APR_PROC_SIGNAL = 2,        /**< process exited due to a signal */
    APR_PROC_SIGNAL_CORE = 4    /**< process exited and dumped a core file */
} apr_exit_why_e;

/** did we exit the process */
#define APR_PROC_CHECK_EXIT(x)        (x & APR_PROC_EXIT)
/** did we get a signal */
#define APR_PROC_CHECK_SIGNALED(x)    (x & APR_PROC_SIGNAL)
/** did we get core */
#define APR_PROC_CHECK_CORE_DUMP(x)   (x & APR_PROC_SIGNAL_CORE)

/** @see apr_procattr_io_set */
#define APR_NO_PIPE          0

/** @see apr_procattr_io_set */
#define APR_FULL_BLOCK       1
/** @see apr_procattr_io_set */
#define APR_FULL_NONBLOCK    2
/** @see apr_procattr_io_set */
#define APR_PARENT_BLOCK     3
/** @see apr_procattr_io_set */
#define APR_CHILD_BLOCK      4

/** @see apr_procattr_limit_set */
#define APR_LIMIT_CPU        0
/** @see apr_procattr_limit_set */
#define APR_LIMIT_MEM        1
/** @see apr_procattr_limit_set */
#define APR_LIMIT_NPROC      2
/** @see apr_procattr_limit_set */
#define APR_LIMIT_NOFILE     3

/**
 * @defgroup APR_OC Other Child Flags
 * @{
 */
#define APR_OC_REASON_DEATH         0     /**< child has died, caller must call
                                           * unregister still */
#define APR_OC_REASON_UNWRITABLE    1     /**< write_fd is unwritable */
#define APR_OC_REASON_RESTART       2     /**< a restart is occuring, perform
                                           * any necessary cleanup (including
                                           * sending a special signal to child)
                                           */
#define APR_OC_REASON_UNREGISTER    3     /**< unregister has been called, do
                                           * whatever is necessary (including
                                           * kill the child) */
#define APR_OC_REASON_LOST          4     /**< somehow the child exited without
                                           * us knowing ... buggy os? */
#define APR_OC_REASON_RUNNING       5     /**< a health check is occuring, 
                                           * for most maintainence functions
                                           * this is a no-op.
                                           */
/** @} */

/** The APR process type */
typedef struct apr_proc_t {
    /** The process ID */
    pid_t pid;
    /** Parent's side of pipe to child's stdin */
    apr_file_t *in;
    /** Parent's side of pipe to child's stdout */
    apr_file_t *out;
    /** Parent's side of pipe to child's stdouterr */
    apr_file_t *err;
#if APR_HAS_PROC_INVOKED || defined(DOXYGEN)
    /** Diagnositics/debugging string of the command invoked for 
     *  this process [only present if APR_HAS_PROC_INVOKED is true]
     * @remark Only enabled on Win32 by default.
     * @bug This should either always or never be present in release
     * builds - since it breaks binary compatibility.  We may enable
     * it always in APR 1.0 yet leave it undefined in most cases.
     */
    char *invoked;
#endif
#if defined(WIN32) || defined(DOXYGEN)
    /** (Win32 only) Creator's handle granting access to the process
     * @remark This handle is closed and reset to NULL in every case
     * corresponding to a waitpid() on Unix which returns the exit status.
     * Therefore Win32 correspond's to Unix's zombie reaping characteristics
     * and avoids potential handle leaks.
     */
    HANDLE hproc;
#endif
} apr_proc_t;

/**
 * The prototype for APR child errfn functions.  (See the description
 * of apr_procattr_child_errfn_set() for more information.)
 * It is passed the following parameters:
 * @param pool Pool associated with the apr_proc_t.  If your child
 *             error function needs user data, associate it with this
 *             pool.
 * @param err APR error code describing the error
 * @param description Text description of type of processing which failed
 */
typedef void (apr_child_errfn_t)(apr_pool_t *proc, apr_status_t err,
                                 const char *description);

/** Opaque Thread structure. */
typedef struct apr_thread_t           apr_thread_t;

/** Opaque Thread attributes structure. */
typedef struct apr_threadattr_t       apr_threadattr_t;

/** Opaque Process attributes structure. */
typedef struct apr_procattr_t         apr_procattr_t;

/** Opaque control variable for one-time atomic variables.  */
typedef struct apr_thread_once_t      apr_thread_once_t;

/** Opaque thread private address space. */
typedef struct apr_threadkey_t        apr_threadkey_t;

/** Opaque record of child process. */
typedef struct apr_other_child_rec_t  apr_other_child_rec_t;

/**
 * The prototype for any APR thread worker functions.
 */
typedef void *(APR_THREAD_FUNC *apr_thread_start_t)(apr_thread_t*, void*);

typedef enum {
    APR_KILL_NEVER,             /**< process is never sent any signals */
    APR_KILL_ALWAYS,            /**< process is sent SIGKILL on apr_pool_t cleanup */
    APR_KILL_AFTER_TIMEOUT,     /**< SIGTERM, wait 3 seconds, SIGKILL */
    APR_JUST_WAIT,              /**< wait forever for the process to complete */
    APR_KILL_ONLY_ONCE          /**< send SIGTERM and then wait */
} apr_kill_conditions_e;

/* Thread Function definitions */

#if APR_HAS_THREADS

/**
 * Create and initialize a new threadattr variable
 * @param new_attr The newly created threadattr.
 * @param cont The pool to use
 */
APR_DECLARE(apr_status_t) apr_threadattr_create(apr_threadattr_t **new_attr, 
                                                apr_pool_t *cont);

/**
 * Set if newly created threads should be created in detached state.
 * @param attr The threadattr to affect 
 * @param on Thread detach state on or off
 */
APR_DECLARE(apr_status_t) apr_threadattr_detach_set(apr_threadattr_t *attr, 
                                                   apr_int32_t on);

/**
 * Get the detach state for this threadattr.
 * @param attr The threadattr to reference 
 */
APR_DECLARE(apr_status_t) apr_threadattr_detach_get(apr_threadattr_t *attr);

/**
 * Set the stack size of newly created threads.
 * @param attr The threadattr to affect 
 * @param stacksize The stack size in bytes
 */
APR_DECLARE(apr_status_t) apr_threadattr_stacksize_set(apr_threadattr_t *attr,
                                                       apr_size_t stacksize);

/**
 * Create a new thread of execution
 * @param new_thread The newly created thread handle.
 * @param attr The threadattr to use to determine how to create the thread
 * @param func The function to start the new thread in
 * @param data Any data to be passed to the starting function
 * @param cont The pool to use
 */
APR_DECLARE(apr_status_t) apr_thread_create(apr_thread_t **new_thread, 
                                            apr_threadattr_t *attr, 
                                            apr_thread_start_t func, 
                                            void *data, apr_pool_t *cont);

/**
 * stop the current thread
 * @param thd The thread to stop
 * @param retval The return value to pass back to any thread that cares
 */
APR_DECLARE(apr_status_t) apr_thread_exit(apr_thread_t *thd, 
                                          apr_status_t retval);

/**
 * block until the desired thread stops executing.
 * @param retval The return value from the dead thread.
 * @param thd The thread to join
 */
APR_DECLARE(apr_status_t) apr_thread_join(apr_status_t *retval, 
                                          apr_thread_t *thd);