libjava/classpath/doc/native.api

GNU Classpath Native State API - Version 0.99.1
Written by Paul Fisher (rao@gnu.org)

For all function calls, if an error occurs, such that `NULL' or a
negative value is returned, it's very possible that an exception has
been thrown from within the function.  The exception is not cleared,
and you are responsible for dealing with the thrown exception.

High level API:

For using the highlevel API, in all cases, OBJ must contain a `final
int' field called "native_state", which has been previously set to the
value of java.lang.System.identityHashCode(OBJ).

Function: struct state_table * init_state_table (JNIEnv *ENV, 
                                                 jclass CLAZZ)

  Creates a state table of default size.  Returns `NULL' on error.

Function: struct state_table * init_state_table_with_size (JNIEnv *ENV,
                                                           jclass CLAZZ,
                                                           jint SIZE)

  Creates a state table, with a tablesize of SIZE.  SIZE should
  always be prime.  Returns `NULL' on error.

Function: jint set_state (JNIEnv *ENV, jobject OBJ, 
                          struct state_table *TABLE, void *STATE)

  Associates STATE with OBJ, in TABLE.  Returns 0 on success, and a
  negative value on failure.  STATE must not be `NULL'.  set_state is
  reentrant, and calls to set_state/get_state/remove_state_slot may be
  made at the same time.
        
Function: void * get_state (JNIEnv *ENV, jobject OBJ,
                            struct state_table *TABLE)

  Retrieves the state associated with OBJ, in TABLE.  Returns `NULL'
  if no value is associated with OBJ, or if a failure occurs.
  get_state is reentrant, and calls to
  get_state/set_state/remove_state_slot may be made at the same time.

Function: void * remove_state_slot (JNIEnv *ENV, jobject OBJ,
                                    struct state_table *TABLE)

  Removes the internal slot associated with OBJ, in TABLE.  Returns a
  pointer to the C state if a state was associated with OBJ,
  otherwise, `NULL' is returned.  After `remove_state' is called,
  `get_state' passing OBJ, will result in `NULL' being returned.  This
  function is generally called in the `finalize' method of a class.
  remove_state_slot is reentrant, and calls to
  get_state/set_state/remove_state_slot may be made at the same time.

Low level API:

Function: void set_state_oid (JNIEnv *ENV, jobject LOCK, 
                              struct state_table *TABLE, 
                              jint OBJECT_ID, void *STATE)

  Associates STATE with OBJECT_ID, in TABLE.  STATE must not be
  `NULL'.  On entering, a lock is obtained on LOCK.  On exiting, the
  lock is released.

Function: void * get_state_oid (JNIEnv *ENV, jobject LOCK, 
                                struct state_table *TABLE, 
                                jint OBJECT_ID)

  Retrieves the state associated with OBJECT_ID, in TABLE.  Returns
  `NULL' if no value is associated with OBJECT_ID.  On entering, a
  lock is obtained on LOCK.  On exiting, the lock is released.

Function: void * remove_state_oid (JNIEnv *ENV, jobject LOCK, 
                                   struct state_table *TABLE, 
                                   jint OBJECT_ID)

  Removes the value associated with OBJECT_ID, in TABLE.  Returns a
  pointer to the C state if a state was associated with OBJECT_ID,
  otherwise, `NULL' is returned.  After `remove_state_oid' is called,
  `get_state_oid' passing OBJECT_ID, will result in `NULL' being
  returned.  On entering, a lock is obtained on LOCK.  On exiting, the
  lock is released.