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#ifndef _GPXE_ASYNC_H
#define _GPXE_ASYNC_H
/** @file
*
* Asynchronous operations
*
*/
#include <gpxe/list.h>
struct async;
/** An asynchronous operation ID
*
* Only positive identifiers are valid; negative values are used to
* indicate errors.
*/
typedef long aid_t;
/** Signals that can be delivered to asynchronous operations */
enum signal {
/** A child asynchronous operation has completed
*
* The parent should call async_wait() to reap the completed
* child. async_wait() will return the exit status and
* operation identifier of the child.
*
* The handler for this signal can be set to @c NULL; if it
* is, then the children will accumulate as zombies until
* async_wait() is called.
*
* The handler for this signal can also be set to @c SIG_IGN;
* if it is, then the children will automatically be reaped.
* Note that if you use @c SIG_IGN then you will not be able
* to retrieve the return status of the children; the call to
* async_wait() will simply return -ECHILD.
*/
SIGCHLD = 0,
/** Cancel asynchronous operation
*
* This signal should trigger the asynchronous operation to
* cancel itself (including killing all its own children, if
* any), and then call async_done(). The asynchronous
* operation is allowed to not complete immediately.
*
* The handler for this signal can be set to @c NULL; if it
* is, then attempts to cancel the asynchronous operation will
* fail and the operation will complete normally. Anything
* waiting for the operation to cancel will block.
*/
SIGKILL,
/** Update progress of asynchronous operation
*
* This signal should cause the asynchronous operation to
* immediately update the @c completed and @c total fields.
*
* The handler for this signal can be set to @c NULL; if it
* is, then the asynchronous operation is expected to keep its
* @c completed and @c total fields up to date at all times.
*/
SIGUPDATE,
SIGMAX
};
/**
* A signal handler
*
* @v async Asynchronous operation
* @v signal Signal received
*/
typedef void ( * signal_handler_t ) ( struct async *async,
enum signal signal );
/** Asynchronous operation operations */
struct async_operations {
/** Reap asynchronous operation
*
* @v async Asynchronous operation
*
* Release all resources associated with the asynchronous
* operation. This will be called only after the asynchronous
* operation itself calls async_done(), so the only remaining
* resources will probably be the memory used by the struct
* async itself.
*
* This method can be set to @c NULL; if it is, then no
* resources will be freed. This may be suitable for
* asynchronous operations that consume no dynamically
* allocated memory.
*/
void ( * reap ) ( struct async *async );
/** Handle signals */
signal_handler_t signal[SIGMAX];
};
/** An asynchronous operation */
struct async {
/** Other asynchronous operations with the same parent */
struct list_head siblings;
/** Child asynchronous operations */
struct list_head children;
/** Parent asynchronous operation
*
* This field is optional; if left to NULL then the owner must
* never call async_done().
*/
struct async *parent;
/** Asynchronous operation ID */
aid_t aid;
/** Final return status code */
int rc;
/** Amount of operation completed so far
*
* The units for this quantity are arbitrary. @c completed
* divded by @total should give something which approximately
* represents the progress through the operation. For a
* download operation, using byte counts would make sense.
*
* This progress indicator should also incorporate the status
* of any child asynchronous operations.
*/
unsigned long completed;
/** Total operation size
*
* See @c completed. A zero value means "total size unknown"
* and is explcitly permitted; users should take this into
* account before calculating @c completed/total.
*/
unsigned long total;
struct async_operations *aop;
};
extern struct async_operations default_async_operations;
extern struct async_operations orphan_async_operations;
extern aid_t async_init ( struct async *async, struct async_operations *aop,
struct async *parent );
extern void async_uninit ( struct async *async );
extern void async_ignore_signal ( struct async *async, enum signal signal );
extern void async_signal ( struct async *async, enum signal signal );
extern void async_signal_children ( struct async *async, enum signal signal );
extern void async_done ( struct async *async, int rc );
extern aid_t async_wait ( struct async *async, int *rc, int block );
/** Default signal handler */
#define SIG_DFL NULL
/** Ignore signal */
#define SIG_IGN async_ignore_signal
/**
* Initialise orphan asynchronous operation
*
* @v async Asynchronous operation
* @ret aid Asynchronous operation ID
*
* An orphan asynchronous operation can act as a context for child
* operations. However, you must not call async_done() on such an
* operation, since this would attempt to send a signal to its
* (non-existent) parent. Instead, simply free the structure (after
* calling async_wait() to ensure that any child operations have
* completed).
*/
static inline aid_t async_init_orphan ( struct async *async ) {
return async_init ( async, &orphan_async_operations, NULL );
}
/**
* Execute and block on an asynchronous operation
*
* @v async_temp Temporary asynchronous operation structure to use
* @v START Code used to start the asynchronous operation
* @ret rc Return status code
*
* This is a notational shorthand for writing
*
* async_init_orphan ( &async_temp );
* if ( ( rc = START ) == 0 )
* async_wait ( &async_temp );
* if ( rc != 0 ) {
* ...handle failure...
* }
*
* and allows you instead to write
*
* if ( ( rc = async_block ( &async_temp, START ) ) != 0 ) {
* ...handle failure...
* }
*
* The argument START is a code snippet; it should initiate an
* asynchronous operation as a child of @c async_temp and return an
* error status code if it failed to do so (e.g. due to malloc()
* failure).
*/
#define async_block( async_temp, START ) ( { \
int rc; \
\
async_init_orphan ( async_temp ); \
if ( ( rc = START ) == 0 ) \
async_wait ( async_temp, &rc, 1 ); \
rc; \
} )
/**
* Execute and block on an asynchronous operation, with progress indicator
*
* @v async_temp Temporary asynchronous operation structure to use
* @v START Code used to start the asynchronous operation
* @ret rc Return status code
*
* As for async_block(), the argument START is a code snippet; it
* should initiate an asynchronous operation as a child of @c
* async_temp and return an error status code if it failed to do so
* (e.g. due to malloc() failure).
*/
#define async_block_progress( async_temp, START ) ( { \
int rc; \
\
async_init_orphan ( async_temp ); \
if ( ( rc = START ) == 0 ) \
async_wait_progress ( async_temp, &rc );\
rc; \
} )
#endif /* _GPXE_ASYNC_H */
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