ACE_Process_Manager Class Reference

Manages a group of processes. More...

#include <Process_Manager.h>

Inheritance diagram for ACE_Process_Manager:

Collaboration diagram for ACE_Process_Manager:

List of all members.

Utility methods

ACE_ALLOC_HOOK_DECLARE

Declare the dynamic allocation hooks.

int register_handler (ACE_Event_Handler *event_handler, pid_t pid=ACE_INVALID_PID)

int remove (pid_t pid)

size_t managed (void) const

Return the number of managed processes.

int set_scheduler (const ACE_Sched_Params &params, pid_t pid)

int set_scheduler_all (const ACE_Sched_Params &params)

void dump (void) const

Dump the state of an object.

Public Types

enum { DEFAULT_SIZE = 100 }

Public Member Functions

Initialization and termination methods

ACE_Process_Manager (size_t size=ACE_Process_Manager::DEFAULT_SIZE, ACE_Reactor *reactor=0)

int open (size_t size=ACE_Process_Manager::DEFAULT_SIZE, ACE_Reactor *r=0)

int close (void)

Release all resources. Do not wait for processes to exit.

virtual ~ACE_Process_Manager (void)

Process creation methods

pid_t spawn (ACE_Process *proc, ACE_Process_Options &options, ACE_Event_Handler *event_handler=0)

pid_t spawn (ACE_Process_Options &options, ACE_Event_Handler *event_handler=0)

int spawn_n (size_t n, ACE_Process_Options &options, pid_t *child_pids=0, ACE_Event_Handler *event_Handler=0)

Process synchronization operations

int terminate (pid_t pid)

int terminate (pid_t pid, int sig)

int wait (const ACE_Time_Value &timeout=ACE_Time_Value::max_time)

pid_t wait (pid_t pid, const ACE_Time_Value &timeout, ACE_exitcode *status=0)

pid_t wait (pid_t pid, ACE_exitcode *status=0)

int reap (pid_t pid=-1, ACE_exitcode *stat_loc=0, int options=WNOHANG)

Static Public Member Functions

Singleton access and control

static ACE_Process_Manager * instance (void)

Get pointer to a process-wide ACE_Process_Manager.

static ACE_Process_Manager * instance (ACE_Process_Manager *)

static void close_singleton (void)

Delete the dynamically allocated singleton.

static void cleanup (void *instance, void *arg)

Protected Member Functions

virtual int handle_signal (int signum, siginfo_t *=0, ucontext_t *=0)

Private Member Functions

int resize (size_t)

Resize the pool of Process_Descriptors.

ssize_t find_proc (pid_t process_id)

ssize_t find_proc (ACE_HANDLE process_handle)

int insert_proc (ACE_Process *process, ACE_Event_Handler *event_handler=0)

int append_proc (ACE_Process *process, ACE_Event_Handler *event_handler=0)

int remove_proc (size_t n)

int notify_proc_handler (size_t n, ACE_exitcode status)

Private Attributes

Process_Descriptor * process_table_

Vector that describes process state within the Process_Manager.

size_t max_process_table_size_

size_t current_count_

Current number of processes we are managing.

ACE_Event_Handler * default_exit_handler_

ACE_Recursive_Thread_Mutex lock_

This lock protects access/ops on process_table_.

Static Private Attributes

static ACE_Process_Manager * instance_ = 0

Singleton pointer.

static bool delete_instance_ = false

Friends

class ACE_Process_Control

Classes

struct Process_Descriptor

Information describing each process that's controlled by an ACE_Process_Manager. More...

Detailed Description

Manages a group of processes.

This class allows applications to control groups of processes, similar to how the ACE_Thread_Manager controls groups of threads. Naturally, it doesn't work at all on platforms, such as VxWorks or pSoS, that don't support process. There are two main ways of using ACE_Process_Manager, depending on how involved you wish to be with the termination of managed processes. If you want processes to simply go away when they're finished, register the ACE_Process_Manager with an ACE_Reactor that can handle notifications of child process exit:

 ACE_Process_Manager mgr;
 // ...
 mgr.open (100, ACE_Reactor::instance ());

In this usage scenario, the ACE_Process_Manager will clean up after any processes that it spawns. (On Unix, this means executing a wait(2) to collect the exit status and avoid zombie processes; on Win32, it means closing the process and thread HANDLEs that are created when CreateProcess is called.)

Note:

When you register a ACE_Process_Manager with a ACE_Reactor, the reactor's notification pipe is used to help reap the available process exit statuses. Therefore, you must not use a reactor whose notify pipe has been disabled. Here's the sequence of steps used to reap the exit statuses in this case:

The ACE_Process_Manager registers a signal handler for SIGCHLD.
The SIGCHLD handler, when invoked, uses the ACE_Reactor's notify() method to inform the ACE_Reactor to wake up.
The ACE_Reactor calls the ACE_Process_Manager's handle_input() method; this happens synchronously, not in signal context.
The handle_input() method collects all available exit statuses.

If, on the other hand you want to wait "in line" to handle the terminated process cleanup code, call one of the wait functions whenever there might be managed processes that have exited.

Note that in either case, ACE_Process_Manager allows you to register an ACE_Event_Handler to be called when a specific spawned process exits, or when any process without a specific ACE_Event_Handler exits. When a process exits, the appropriate ACE_Event_Handler's handle_input() method is called; the ACE_HANDLE passed is either the process's HANDLE (on Win32), or its pid cast to an ACE_HANDLE (on POSIX). It is also possible to call the wait() functions even when the ACE_Process_Manager is registered with a reactor.

Note:: Be aware that the wait functions are "sloppy" on Unix, because there's no good way to wait for a subset of the children of a process. The wait functions may end up collecting the exit status of a process that's not managed by the ACE_Process_Manager whose wait() you invoked. It's best to only use a single ACE_Process_Manager, and to create all subprocesses by calling that manager's spawn() method.

Member Enumeration Documentation

anonymous enum

Enumerator:

DEFAULT_SIZE

Constructor & Destructor Documentation

ACE_Process_Manager::ACE_Process_Manager	(	size_t	size = `ACE_Process_Manager::DEFAULT_SIZE`,
		ACE_Reactor *	reactor = `0`
	)

Initialize an ACE_Process_Manager with a table containing up to size processes. This table resizes itself automatically as needed. If a reactor is provided, this ACE_Process_Manager uses it to notify an application when a process it controls exits. By default, however, we don't use an ACE_Reactor.

ACE_Process_Manager::~ACE_Process_Manager ( void ) [virtual]

Destructor releases all resources and does not wait for processes to exit.

Member Function Documentation

int ACE_Process_Manager::open	(	size_t	size = `ACE_Process_Manager::DEFAULT_SIZE`,
		ACE_Reactor *	r = `0`
	)

Initialize an ACE_Process_Manager with a table containing up to size processes. This table resizes itself automatically as needed. If a reactor is provided, this ACE_Process_Manager uses it to notify an application when a process it controls exits. By default, however, we don't use an ACE_Reactor.

int ACE_Process_Manager::close ( void )

Release all resources. Do not wait for processes to exit.

ACE_Process_Manager * ACE_Process_Manager::instance ( void ) [static]

Get pointer to a process-wide ACE_Process_Manager.

ACE_Process_Manager * ACE_Process_Manager::instance ( ACE_Process_Manager * tm ) [static]

Set pointer to a process-wide ACE_Process_Manager and return existing pointer.

void ACE_Process_Manager::close_singleton ( void ) [static]

Delete the dynamically allocated singleton.

ACE_BEGIN_VERSIONED_NAMESPACE_DECL void ACE_Process_Manager::cleanup	(	void *	instance,
		void *	arg
	)			`[static]`

Cleanup method, used by the ACE_Object_Manager to destroy the singleton.

pid_t ACE_Process_Manager::spawn	(	ACE_Process *	proc,
		ACE_Process_Options &	options,
		ACE_Event_Handler *	event_handler = `0`
	)

Create a new process with specified options. Register event_handler to be called back when the process exits.

On success, returns the process id of the child that was created. On failure, returns ACE_INVALID_PID.

pid_t ACE_Process_Manager::spawn	(	ACE_Process_Options &	options,
		ACE_Event_Handler *	event_handler = `0`
	)

Create a new process with the specified options. Register event_handler to be called back when the process exits.

On success, returns the process id of the child that was created. On failure, returns ACE_INVALID_PID.

int ACE_Process_Manager::spawn_n	(	size_t	n,
		ACE_Process_Options &	options,
		pid_t *	child_pids = `0`,
		ACE_Event_Handler *	event_Handler = `0`
	)

Create n new processes with the same options. If child_pids is non-0 it is expected to be an array of at least n pid_t, which are filled in with the process IDs of the spawned processes. Register event_handler to be called back when each process exits. Returns 0 on success and -1 on failure.

int ACE_Process_Manager::terminate ( pid_t pid )

Abruptly terminate a single process with id pid using the ACE::terminate_process() method which works on both signal-capable systems and on Windows.

Note:: This call is potentially dangerous to use since the process being terminated may not have a chance to cleanup before it shuts down.

Return values:

0

on success and -1 on failure.

int ACE_Process_Manager::terminate	(	pid_t	pid,
		int	sig
	)

Sends the specified signal to the specified process.

Note:: This only works on platforms that have signal capability. In particular, it doesn't work on Windows.

Return values:

0

on success and -1 on failure.

int ACE_Process_Manager::wait ( const ACE_Time_Value & timeout = ACE_Time_Value::max_time )

Block until there are no more child processes running that were spawned by this ACE_Process_Manager. Unlike the wait() method below, this method does not require a signal handler or use of ACE_OS::sigwait() because it simply blocks synchronously waiting for all the children managed by this ACE_Process_Manager to exit. Note that this does not return any status information about the success or failure of exiting child processes, although any registered exit handlers are called.

Parameters:

timeout

Relative time to wait for processes to terminate.

Return values:

0

on success; -1 on failure.

pid_t ACE_Process_Manager::wait	(	pid_t	pid,
		const ACE_Time_Value &	timeout,
		ACE_exitcode *	status = `0`
	)

Wait up to timeout for a single specified process to terminate. If pid is 0, this method waits for any of the managed processes (but see the note concerning "sloppy process cleanup on unix"). If pid != 0, waits for that process only.

Parameters:

	pid	Process ID
	timeout	Relative time to wait for process to terminate
	status	Exit status of terminated process

Return values:

The

pid of the process which exited, 0 if a timeout occurred, or ACE_INVALID_PID on error.

pid_t ACE_Process_Manager::wait	(	pid_t	pid,
		ACE_exitcode *	status = `0`
	)

Wait indefinitely for a single, specified process to terminate. If pid is 0, waits for any of the managed processes (but see the note concerning "sloppy process cleanup on unix"). If pid != 0, this method waits for that process only.

Return values:

The

pid of the process which exited, or ACE_INVALID_PID on error.

int ACE_Process_Manager::reap	(	pid_t	pid = `-1`,
		ACE_exitcode *	stat_loc = `0`,
		int	options = `WNOHANG`
	)

Deprecated:: Reap the result of a single process by calling ACE_OS::waitpid(), therefore, this method is not portable to Windows. If the child is successfully reaped, remove() is called automatically. Use one of the wait() methods instead of this method.

int ACE_Process_Manager::register_handler	(	ACE_Event_Handler *	event_handler,
		pid_t	pid = `ACE_INVALID_PID`
	)

Register an event handler to be called back when the specified process exits. If pid == ACE_INVALID_PID this handler is called when any process with no specific handler exits.

Warning:: In multithreaded applications, there is a race condition if a process exits between the time it is spawned and when its handler is registered. To avoid this, register the handler at the time the process is spawned.

int ACE_Process_Manager::remove ( pid_t pid )

Remove process pid from the ACE_Process_Manager's internal records. This is called automatically by the reap() method after it successfully reaps a process. It's also possible to call this method directly from a signal handler, but don't call both reap() and remove()!

ACE_BEGIN_VERSIONED_NAMESPACE_DECL ACE_INLINE size_t ACE_Process_Manager::managed ( void ) const

Return the number of managed processes.

int ACE_Process_Manager::set_scheduler	(	const ACE_Sched_Params &	params,
		pid_t	pid
	)

Sets the scheduling parameters for process identified by pid by passing params, pid to ACE_OS::sched_params().

Return values:

0

on success, -1 on failure, and ACE_INVALID_PID when the specified pid is not managed by this ACE_Process_Manager.

int ACE_Process_Manager::set_scheduler_all ( const ACE_Sched_Params & params )

Sets the scheduling parameters for all the processes managed by this ACE_Process_Manager by passing params to ACE_OS::sched_params().

Return values:

0

on success, -1 on failure.

void ACE_Process_Manager::dump ( void ) const

Dump the state of an object.

int ACE_Process_Manager::handle_signal	(	int	signum,
		siginfo_t *	si = `0`,
		ucontext_t *	= `0`
	)			`[protected, virtual]`

On Unix, this routine is called asynchronously when a SIGCHLD is received. We just tweak the reactor so that it'll call back our <handle_input> function, which allows us to handle Process exits synchronously.

On Win32, this routine is called synchronously, and is passed the HANDLE of the Process that exited, so we can do all our work here

Reimplemented from ACE_Event_Handler.

int ACE_Process_Manager::resize ( size_t size ) [private]

Resize the pool of Process_Descriptors.

ssize_t ACE_Process_Manager::find_proc ( pid_t process_id ) [private]

Locate the index of the table slot occupied by process_id. Returns -1 if process_id is not in the process_table_

ssize_t ACE_Process_Manager::find_proc ( ACE_HANDLE process_handle ) [private]

Locate the index of the table slot occupied by process_handle. Returns ~0 if process_handle is not in the process_table_

int ACE_Process_Manager::insert_proc	(	ACE_Process *	process,
		ACE_Event_Handler *	event_handler = `0`
	)			`[private]`

Insert a process in the table (checks for duplicates). Omitting the process handle won't work on Win32... Register event_handler to be called back when the process exits.

int ACE_Process_Manager::append_proc	(	ACE_Process *	process,
		ACE_Event_Handler *	event_handler = `0`
	)			`[private]`

Append information about a process, i.e., its <process_id> in the process_table_. Each entry is added at the end, growing the table if necessary. Register event_handler to be called back when the process exits.

int ACE_Process_Manager::remove_proc ( size_t n ) [private]

Actually removes the process at index n from the table. This method must be called with locks held.

int ACE_Process_Manager::notify_proc_handler	(	size_t	n,
		ACE_exitcode	status
	)			`[private]`

If there's a specific handler for the Process at index n in the table, or there's a default handler, call it.

Friends And Related Function Documentation

friend class ACE_Process_Control [friend]

Member Data Documentation

ACE_Process_Manager::ACE_ALLOC_HOOK_DECLARE

Declare the dynamic allocation hooks.

Process_Descriptor* ACE_Process_Manager::process_table_ [private]

Vector that describes process state within the Process_Manager.

size_t ACE_Process_Manager::max_process_table_size_ [private]

Maximum number of processes we can manage (should be dynamically allocated).

size_t ACE_Process_Manager::current_count_ [private]

Current number of processes we are managing.

ACE_Event_Handler* ACE_Process_Manager::default_exit_handler_ [private]

This event handler is used to notify when a process we control exits.

ACE_Process_Manager * ACE_Process_Manager::instance_ = 0 [static, private]

Singleton pointer.

bool ACE_Process_Manager::delete_instance_ = false [static, private]

Controls whether the <Process_Manager> is deleted when we shut down (we can only delete it safely if we created it!)

ACE_Recursive_Thread_Mutex ACE_Process_Manager::lock_ [private]

This lock protects access/ops on process_table_.

The documentation for this class was generated from the following files:


Utility methods
	ACE_ALLOC_HOOK_DECLARE
	Declare the dynamic allocation hooks.
int	register_handler (ACE_Event_Handler *event_handler, pid_t pid=ACE_INVALID_PID)
int	remove (pid_t pid)
size_t	managed (void) const
	Return the number of managed processes.
int	set_scheduler (const ACE_Sched_Params &params, pid_t pid)
int	set_scheduler_all (const ACE_Sched_Params &params)
void	dump (void) const
	Dump the state of an object.
Public Types
enum	{ DEFAULT_SIZE = 100 }
Public Member Functions
Initialization and termination methods
	ACE_Process_Manager (size_t size=ACE_Process_Manager::DEFAULT_SIZE, ACE_Reactor *reactor=0)
int	open (size_t size=ACE_Process_Manager::DEFAULT_SIZE, ACE_Reactor *r=0)
int	close (void)
	Release all resources. Do not wait for processes to exit.
virtual	~ACE_Process_Manager (void)
Process creation methods
pid_t	spawn (ACE_Process proc, ACE_Process_Options &options, ACE_Event_Handler event_handler=0)
pid_t	spawn (ACE_Process_Options &options, ACE_Event_Handler *event_handler=0)
int	spawn_n (size_t n, ACE_Process_Options &options, pid_t child_pids=0, ACE_Event_Handler event_Handler=0)
Process synchronization operations
int	terminate (pid_t pid)
int	terminate (pid_t pid, int sig)
int	wait (const ACE_Time_Value &timeout=ACE_Time_Value::max_time)
pid_t	wait (pid_t pid, const ACE_Time_Value &timeout, ACE_exitcode *status=0)
pid_t	wait (pid_t pid, ACE_exitcode *status=0)
int	reap (pid_t pid=-1, ACE_exitcode *stat_loc=0, int options=WNOHANG)
Static Public Member Functions
Singleton access and control
static ACE_Process_Manager *	instance (void)
	Get pointer to a process-wide ACE_Process_Manager.
static ACE_Process_Manager *	instance (ACE_Process_Manager *)
static void	close_singleton (void)
	Delete the dynamically allocated singleton.
static void	cleanup (void instance, void arg)
Protected Member Functions
virtual int	handle_signal (int signum, siginfo_t =0, ucontext_t =0)
Private Member Functions
int	resize (size_t)
	Resize the pool of Process_Descriptors.
ssize_t	find_proc (pid_t process_id)
ssize_t	find_proc (ACE_HANDLE process_handle)
int	insert_proc (ACE_Process process, ACE_Event_Handler event_handler=0)
int	append_proc (ACE_Process process, ACE_Event_Handler event_handler=0)
int	remove_proc (size_t n)
int	notify_proc_handler (size_t n, ACE_exitcode status)
Private Attributes
Process_Descriptor *	process_table_
	Vector that describes process state within the Process_Manager.
size_t	max_process_table_size_
size_t	current_count_
	Current number of processes we are managing.
ACE_Event_Handler *	default_exit_handler_
ACE_Recursive_Thread_Mutex	lock_
	This lock protects access/ops on `process_table_`.
Static Private Attributes
static ACE_Process_Manager *	instance_ = 0
	Singleton pointer.
static bool	delete_instance_ = false
Friends
class	ACE_Process_Control
Classes
struct	Process_Descriptor
	Information describing each process that's controlled by an ACE_Process_Manager. More...