Named Semaphore
Named semaphore for Linux & Windows.
To use this crate, add the following to Cargo.toml
:
[]
= "0.1"
Background
Named semaphore is a process synchronize mechanism provided by OS and libc in Linux & Windows. By giving the semaphore a name, processes with appropriate permissions can share the same semaphore.
In Linux, we use the POSIX semaphore as implementation, and in Windows, we use Semaphore Objects.
Examples
use ;
#
Usage
A common usage for named semaphore is to control the process count across the system.
For example, we have four large directories, A
, B
, C
and D
, which needs to be compressed. While our computer's hardware only allows for two 7z
processes to run at the same time. So we can create a named semaphore with initial value 2, and require the semaphore before each 7z
run.
There is a small utility, preempt-do
, in this repo. Compile it by
cargo build --release --features=commandline --bin preempt-do
Or you can install it by
cargo install named-sem --features=commandline --bin preempt-do
Then you can use the following instructions to do the things above:
preempt-do --name /my-semaphore --count 2 -- 7z a A.7z A
preempt-do --name /my-semaphore --count 2 -- 7z a B.7z B
preempt-do --name /my-semaphore --count 2 -- 7z a C.7z C
preempt-do --name /my-semaphore --count 2 -- 7z a D.7z D
This will allow there to be no more than two 7z
processes across the system.