Description:
Use a synchronization lock.
Syntax:
lock(n,s)
Note:
The function enforces limits on access to a file in an multithreading execution environment using lock-based synchronization. With the lock, only one thread can access and process the file at a time.
Parameter:
|
n |
Lock name |
|
s |
Timeout (in millisecond); waiting to be locked if the parameter is absent |
Option:
|
@u |
Unlock the restriction |
Return value:
Lock name
Example:
Locking:
|
|
A |
|
|
1 |
=lock(1) |
Use a lock named 1 |
|
2 |
>output("Task "/arg1/" start...") |
Output the parameter and start to calculate |
|
3 |
=file("D:/file/test/1.btx") |
Create a btx file |
|
4 |
=create(ID,Value) |
Create a table sequence |
|
5 |
>A4.record([arg1,arg1*arg1]) |
Add records to A4’s table sequence |
|
6 |
>sleep(1000) |
Make the system sleep for 1000 miliseconds |
|
7 |
>A3.export@ab(A4) |
Write A4’s table sequence into the btx file |
|
8 |
>output("Task "/arg1/" finished.") |
Output the parameter and finish the calculation |
|
9 |
>lock@u(1) |
Unlock the access restriction |
File access:
|
|
A |
|
|
1 |
=file("D:/file/test/1.btx") |
|
|
2 |
D:\test \lock1.dfx |
|
|
3 |
=callx(A2,to(100)) |
When using callx() function to acess a file, the max number of parallel task set in Tool -> Options should be greater than 1 in case that the lock-based synchronization reports an error |
|
4 |
=A1.import@b() |
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