![[OPUS]](opus.gif)
This class is available for the OPUS Blackboard API. The initial OPUS 2.0 release is described here
Constructors:
| File_pstat_lock( ) | |
| ~File_pstat_lock( ) |
Methods:
| assign( ) | sets the target file |
| lock( ) | locks the target file |
| release( ) | releases the lock |
| operator==( ) | tests locks for equality |
| get_target( ) | gets copy of locked PSTAT file as a File_pstat object |
Description
This class manages lock files for PSTAT entries that are stored on the file system. A masked version of the target file name is stored in a subdirectory of the PSTAT blackboard directory and serves as the lock. The mask pads all fields except the unique, identifying fields in each entry (the Pid and Node fields). Because the mask does not contain all of the information in the target PSTAT file name, a copy of the locked file name at the time the lock is obtained is maintained by this object for reference.
Derived from
Pstat_lock, private Opus_lock_file
See Also:
File_pstat_lock::File_pstat_lock - The File_pstat_lock object constructor.
Synopsis
File_pstat_lock::File_pstat_lock() : locked_ent(0)
File_pstat_lock::File_pstat_lock(
const File_pstat* ent, // I - PSTAT file
// to lock
const std::string& dir) // I - directory
// containing
// the PSTAT
// files
Description
The constructor creates an Opus_lock_file object for the indicated PSTAT file, if supplied.
Exceptions Thrown
| Bad_val<string> | - if the string does not appear to be a directory specification or invalid characters are present; Bad_val.arg contains the calling argument |
| Io_error<int> | - if a problem occurs determining the current working directory; Io_error.arg contains the value of errno |
| Bad_val<string> | - if the string contains invalid characters; Bad_val.arg contains the calling argument |
| Bad_val<string> | - if the extension prefix is not present or invalid characters are present; Bad_val.arg contains the calling argument |
| Bad_val<string> | - if dangle prefix is not present or invalid characters are present; Bad_val.arg contains the calling argument |
| Io_error<int> | - if an IO error occurs creation of the lock directory; Io_error.arg contains the value of errno |
| Bad_val<File_pstat*> | - if the first argument is null; Bad_val.arg points to the first argument |
File_pstat_lock::~File_pstat_lock - The File_pstat_lock object destructor.
Synopsis
File_pstat_lock::~File_pstat_lock()
Description
The destructor destroys the object and deletes its internal copy of the target File_pstat object.
Exceptions Thrown
File_pstat_lock::lock - Attempt to lock the PSTAT file.
Synopsis
void File_pstat_lock::lock()
Description
An attempt is made to lock the target up to three times.
Exceptions Thrown
| Locked<string> | - if the target file is locked already; Locked.arg contains the target name |
| Io_error<int> | - if an IO error occurs during the lock attempt; Io_error.arg contains the value of errno |
| Bad_val<string> | - if the stretch cannot be resolved; Bad_val.arg contains the stretched file name |
| Bad_val<vector<string>> | - if the calling arguments are incorrect; Bad_val.arg is a vector containing the calling arguments |
| Io_error<int> | - if the disk space check fails; Io_error.arg contains the value of errno |
| Bad_val<vector<string>> | - if calling arguments are incorrect; Bad_val.arg is a vector containing the calling arguments |
| Exec<int> | - if the subprocess spawn attempt fails; Exec.arg contains the return status from the spawn attemp |
| Bad_val<string> | - if the string does not appear to be a directory specification or invalid characters are present; Bad_val.arg contains the calling argument |
| Io_error<int> | - if a problem occurs determining the current working directory; Io_error.arg contains the value of errno |
| Bad_val<string> | - if the string contains invalid characters; Bad_val.arg contains the calling argument |
| Bad_val<string> | - if the extension prefix is not present or invalid characters are present; Bad_val.arg contains the calling argument |
| Bad_val<string> | - if dangle prefix is not present or invalid characters are present; Bad_val.arg contains the calling argument |
| Io_error<int> | - if an IO error occurs creation of the lock directory; Io_error.arg contains the value of errno |
File_pstat_lock::release - Release lock on PSTAT file.
Synopsis
void File_pstat_lock::release()
Description
This method deletes the lock file, if one is present and the file is locked.
Exceptions Thrown
| Io_error<int> | - if an IO error occurs during delete; Io_error.arg contains the value of errno |
File_pstat_lock::operator== - Compare the File_pstat_lock object with another.
Synopsis
bool File_pstat_lock::operator==(
const Opus_lock* ol) // I - lock to compare
// to
const
Description
This operator compares the object with the File_pstat_lock object argument. Two File_pstat_lock objects are equal if the lock file names are identical.
***Note that a pointer (not a reference) to the object with which the comparison is to be made is required.
Returns
true - if the locks are identical
false - if the locks are not identical
Exceptions Thrown
File_pstat_lock::get_target - Get a copy of the target PSTAT file as a File_pstat object.
Synopsis
Pstat* File_pstat_lock::get_target() const
Description
A copy of the locked File_pstat object is fetched off disk (if necessary), and a copy is constructed off the heap and returned to the caller. The target must be locked prior to calling this method. The client should delete the new object when it is no longer needed.
Returns
The File_pstat object that is the target of this lock.
Exceptions Thrown
| Not_ready<void*> | - if the target has not been locked; Not_ready.arg points to null. |
| Io_error<const char*> | - if an IO error occurs while searching for the file; Io_error.arg contains the error message |
Copyright © 1997-2000 The Association of Universities for
Research in Astronomy, Inc. All Rights Reserved.
For more information, contact opushelp@stsci.edu
Last modified: 25 April 2000