Ns critsec
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Man page: http://aolserver.com/docs/tcl/ns_critsec.html
NAME
- ns_critsec - Operate on critical section objects
SYNOPSIS
- ns_critsec option ?arg arg ...?
DESCRIPTION
- This command provides a mechanism to manipulate critical section objects. The legal options (which may be abbreviated) are:
- ns_critsec create
- Initializes a new critical section object and returns a handle to it.
- ns_critsec destroy object
- Destroys the critical section object and frees any resources it was using.
- ns_critsec enter object
- Enters the critical section. The thread will block if another thread is already in the critical section.
- ns_critsec leave object
- Leaves the critical section. When the thread leaves the critical section as many times as it has entered, a notification will be sent to other threads that are waiting on the critical section.
EXAMPLES
Is this the right way to use this command? The example is contrived, but I wanted to call ns_critsec multiple times.
# If a thread is executing any of these procs, no other # thread can execute any of these procs until the first # thread has completely finished. nsv_set . special_file_critsec [ns_critsec create] proc write_special_file {data} { set critsec [nsv_get . special_file_critsec] ns_critsec enter $critsec set handle [open special_file w] puts $handle $data close $handle ns_critsec leave $critsec } proc read_special_file {} { set critsec [nsv_get . special_file_critsec] ns_critsec enter $critsec set handle [open special_file r] set result [read $handle] close $handle ns_critsec leave $critsec return $result } proc change_special_file {data} { set critsec [nsv_get . special_file_critsec] ns_critsec enter $critsec set result [read_special_file] write_special_file $data ns_critsec leave $critsec return $result }
SEE ALSO