Package org.apache.tomcat.jni
Class Lock
- java.lang.Object
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- org.apache.tomcat.jni.Lock
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public class Lock extends Object
Lock- Author:
- Mladen Turk
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Field Summary
Fields Modifier and Type Field Description static intAPR_LOCK_DEFAULTPOSIX semaphore process-based lockingstatic intAPR_LOCK_FCNTLEnumerated potential types for APR process locking methods
Warning : Check APR_HAS_foo_SERIALIZE defines to see if the platform supports APR_LOCK_foo.static intAPR_LOCK_FLOCKfcntl()static intAPR_LOCK_POSIXSEMPOSIX pthread process-based lockingstatic intAPR_LOCK_PROC_PTHREADSystem V Semaphoresstatic intAPR_LOCK_SYSVSEMflock()
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Constructor Summary
Constructors Constructor Description Lock()
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static longchildInit(String fname, long pool)Re-open a mutex in a child process.static longcreate(String fname, int mech, long pool)Create and initialize a mutex that can be used to synchronize processes.static Stringdefname()Display the name of the default mutex: APR_LOCK_DEFAULTstatic intdestroy(long mutex)Destroy the mutex and free the memory associated with the lock.static intlock(long mutex)Acquire the lock for the given mutex.static Stringlockfile(long mutex)Return the name of the lockfile for the mutex, or NULL if the mutex doesn't use a lock filestatic Stringname(long mutex)Display the name of the mutex, as it relates to the actual method used.static inttrylock(long mutex)Attempt to acquire the lock for the given mutex.static intunlock(long mutex)Release the lock for the given mutex.
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Field Detail
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APR_LOCK_FCNTL
public static final int APR_LOCK_FCNTL
Enumerated potential types for APR process locking methods
Warning : Check APR_HAS_foo_SERIALIZE defines to see if the platform supports APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.- See Also:
- Constant Field Values
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APR_LOCK_FLOCK
public static final int APR_LOCK_FLOCK
fcntl()- See Also:
- Constant Field Values
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APR_LOCK_SYSVSEM
public static final int APR_LOCK_SYSVSEM
flock()- See Also:
- Constant Field Values
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APR_LOCK_PROC_PTHREAD
public static final int APR_LOCK_PROC_PTHREAD
System V Semaphores- See Also:
- Constant Field Values
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APR_LOCK_POSIXSEM
public static final int APR_LOCK_POSIXSEM
POSIX pthread process-based locking- See Also:
- Constant Field Values
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APR_LOCK_DEFAULT
public static final int APR_LOCK_DEFAULT
POSIX semaphore process-based locking- See Also:
- Constant Field Values
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Method Detail
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create
public static long create(String fname, int mech, long pool) throws Error
Create and initialize a mutex that can be used to synchronize processes.
Warning : Check APR_HAS_foo_SERIALIZE defines to see if the platform supports APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.- Parameters:
fname- A file name to use if the lock mechanism requires one. This argument should always be provided. The lock code itself will determine if it should be used.mech- The mechanism to use for the interprocess lock, if any; one ofAPR_LOCK_FCNTL APR_LOCK_FLOCK APR_LOCK_SYSVSEM APR_LOCK_POSIXSEM APR_LOCK_PROC_PTHREAD APR_LOCK_DEFAULT pick the default mechanism for the platformpool- the pool from which to allocate the mutex.- Returns:
- Newly created mutex.
- Throws:
Error- An error occurred
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childInit
public static long childInit(String fname, long pool) throws Error
Re-open a mutex in a child process. This function must be called to maintain portability, even if the underlying lock mechanism does not require it.- Parameters:
fname- A file name to use if the mutex mechanism requires one. This argument should always be provided. The mutex code itself will determine if it should be used. This filename should be the same one that was passed to apr_proc_mutex_create().pool- The pool to operate on.- Returns:
- Newly opened mutex.
- Throws:
Error- An error occurred
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lock
public static int lock(long mutex)
Acquire the lock for the given mutex. If the mutex is already locked, the current thread will be put to sleep until the lock becomes available.- Parameters:
mutex- the mutex on which to acquire the lock.- Returns:
- the operation status
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trylock
public static int trylock(long mutex)
Attempt to acquire the lock for the given mutex. If the mutex has already been acquired, the call returns immediately with APR_EBUSY. Note: it is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine if the return value was APR_EBUSY, for portability reasons.- Parameters:
mutex- the mutex on which to attempt the lock acquiring.- Returns:
- the operation status
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unlock
public static int unlock(long mutex)
Release the lock for the given mutex.- Parameters:
mutex- the mutex from which to release the lock.- Returns:
- the operation status
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destroy
public static int destroy(long mutex)
Destroy the mutex and free the memory associated with the lock.- Parameters:
mutex- the mutex to destroy.- Returns:
- the operation status
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lockfile
public static String lockfile(long mutex)
Return the name of the lockfile for the mutex, or NULL if the mutex doesn't use a lock file- Parameters:
mutex- the name of the mutex- Returns:
- the name of the lock file
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name
public static String name(long mutex)
Display the name of the mutex, as it relates to the actual method used. This matches the valid options for Apache's AcceptMutex directive- Parameters:
mutex- the name of the mutex- Returns:
- the name of the mutex
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defname
public static String defname()
Display the name of the default mutex: APR_LOCK_DEFAULT- Returns:
- the default name
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