Module Semaphore.Counting

Instructions: Use this module in your project

In the IDE (CLion, Visual Studio Code, Xcode, etc.) you use for your DkSDK project:

Add the following to your project's dependencies/CMakeLists.txt:

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DkSDKProject_DeclareAvailable(ocaml
    CONSTRAINT "= 4.14.0"
    FINDLIBS str unix runtime_events threads dynlink)
DkSDKProject_MakeAvailable(ocaml)

Add the Findlib::ocaml library to any desired targets in src/*/CMakeLists.txt:

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target_link_libraries(YourPackage_YourLibraryName
     # ... existing libraries, if any ...
     Findlib::ocaml)

Click your IDE's Build button

Not using DkSDK?

FIRST, do one or all of the following:

Run:
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```
opam install ocaml.4.14.0
```

Edit your dune-project and add:

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(package
  (name YourExistingPackage)
  (depends
  ; ... existing dependenices ...
  (ocaml (>= 4.14.0))))

Then run:

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dune build *.opam # if this fails, run: dune build

Edit your <package>.opam file and add:

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depends: [
  # ... existing dependencies ...
  "ocaml" {>= "4.14.0"}
]

Then run:

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opam install . --deps-only

FINALLY, add the unix threads library to any desired (library)and/or (executable) targets in your **/dune files:

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(library
  (name YourLibrary)
  ; ... existing library options ...
  (libraries
    ; ... existing libraries ...
    unix threads))

(executable
  (name YourExecutable)
  ; ... existing executable options ...
  (libraries
    ; ... existing libraries ...
    unix threads))

type t

The type of counting semaphores.

valmake : ``int-> t

make n returns a new counting semaphore, with initial value n. The initial value n must be nonnegative.

raises Invalid_argument

if n < 0

valrelease :t -> unit

release s increments the value of semaphore s. If other threads are waiting on s, one of them is restarted. If the current value of s is equal to max_int, the value of the semaphore is unchanged and a Sys_error exception is raised to signal overflow.

raises Sys_error

if the value of the semaphore would overflow max_int

valacquire :t -> unit

acquire s blocks the calling thread until the value of semaphore s is not zero, then atomically decrements the value of s and returns.

valtry_acquire :t -> bool

try_acquire s immediately returns false if the value of semaphore s is zero. Otherwise, the value of s is atomically decremented and try_acquire s returns true.

valget_value :t -> int

get_value s returns the current value of semaphore s. The current value can be modified at any time by concurrent release and acquire operations. Hence, the get_value operation is racy, and its result should only be used for debugging or informational messages.

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