Nils O. Selåsdal
81 lines
2.5 KiB
C
81 lines
2.5 KiB
C
#ifndef UC_RESTART_COUNTER_H_
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#define UC_RESTART_COUNTER_H_
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/** @file
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* Simple support for keeping track of number of restarts.
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*
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* Certain protocols desire support for comminicating the number
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* of times an entity has restarted.
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* The counter might also serve as a seed for sequence number generation
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* to minimize recycling a recently used sequence number.
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*
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* The number of times a process has been restarted is simply kept
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* track of via a counter in a restart state ile in ascii representation.
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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struct UCRestartCounter {
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unsigned int counter;
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int fd;
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};
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typedef enum {
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UC_RC_OK,
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/** accessing the file failed, inspect errno
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* for more info */
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UC_RC_ERR_FILE_ACCESS_ERROR,
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/* The file existed and is opened but
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* no valid number could be read from the file.
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* This is a transient error,
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* the now new counter is initialized to 0, and
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* written to the file */
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UC_RC_ERR_FILE_CONTENT_ERROR,
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/* UC_RC_FL_LOCK_FILE was specified but the file
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* is already locked by some other process */
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UC_RC_ERR_FILE_LOCKED,
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/** unspecified error. Inspect errno. */
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UC_RC_ERR_UNSPECIFIED,
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/** Given by uc_restart_counter_close if the
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* file never was opened */
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UC_RC_ERR_NOT_OPENED,
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} UCRCResult;
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/** Lock the restart state file and keep it open.
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* e.g. to prevent several processes from being started
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* and using the same restart state file.*/
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#define UC_RC_FL_LOCK_FILE ( 1 << 0)
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/** Read and update the current restart counter.
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* This is typically called once at program startup.
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*
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* @param counter the counter to initialize
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* @param filename the filename to use to keep track of the state
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* @param flags one of UC_RC_FL_XX
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*/
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UCRCResult uc_restart_counter_init(struct UCRestartCounter *counter,
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const char *filename,
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unsigned int flags);
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/** Close the current restart counter file if it was opened with the
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* UC_RC_FL_LOCK_FILE flag.
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*
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* @counter counter file to close. (uc_restart_counter can still be called
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* after * the file is closed)
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* @return UC_RC_OK or if the file was not kept open with UC_RC_ERR_FILE_LOCKED
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*/
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UCRCResult uc_restart_counter_close(struct UCRestartCounter *counter);
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/** Get the current restart counter.
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* In case uc_restart_counter_init failed, this will return 0.
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*/
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unsigned int uc_restart_counter_get(const struct UCRestartCounter *counter);
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#ifdef __cplusplus
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}
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#endif
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#endif
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