Task Orch

System Composition

The entire concurrency library can generally be divided into four main components:

• Task — The minimal unit of execution, built from a fn or closure along with runtime metadata.
• Queue — The queue holds tasks that are waiting to be processed. It acts as a buffer where tasks are stored until they can be executed.
• Threads — Threads are responsible for executing the tasks retrieved from the queue.
• Resource Pool — Responsible for the lifecycle management of both the Queue and the Threads, establishing a mapping between names and instances.

Task

Task Modes

Tasks can be executed in two distinct modes:

• Independent: Runs freely without constraint.
• Conditional: Executes only when all conditions are satisfied.

Task Flow

1. Activation:
   A task is scheduled once all its required conditions are fulfilled.
2. Execution:
   The task runs and computes its return value.
3. Data Passing:
   If a target anchor is configured, the return value will be passed on to another task.

Key Notes:

• Conditions correspond to the function’s parameters (0-indexed).

Task ID Assignment

• Explicit ID: You can provide your own ID using a generator or by calling taskid_next().
• Auto-generated: If you omit specifying an ID, the system will automatically assign one.

Building a Task (3-Step Process)

1. Prepare: Define a function or closure.
2. Create: Create the task chained by .task().
3. Notify (Optional): Chain tasks by calling to() to set a target anchor.
   This step can be skipped if the task does not produce any output.

Task Creation Code

⚠️ Type cast NOTE

❗ Error-prone operation!
When forwarding a task result to a conditional task's condition point:

• Ensure the result type must be identical to the condition type.
• Violation will trigger panic!

# use taskorch::{TaskBuildNew as _, TaskBuildOp as _};
// Sample code explanation
let cc = |a:i32,b:i8|{}; // the type of cond #0 is `i32`
                         // the type of cond #1 is `i8` 
let f0 = ||5i32; // the return type is `i32`
let f1 = ||5i8;  // the return type is `i8`

let task_cc = (cc,1).task(); /// taskid is explicitly set to 1
let task_f0 = f0.task().to(1,0); // *** return type `i32` === cond #0 type `i32` ***
let task_f1 = f1.task().to(1,1); // *** return type `i8` === cond #1 type `i8`   ***

Note

NO parameter, NO taskid needed.
NO return, NO target anchor required.

Case 1: [ No parameter, No return ]

# use taskorch::TaskBuildNew as _;
let task = 
    (||{})          // <1> Define the body
        .task();    // <2> Create a task from the given closure.
                    // <3> `to()` skipped, as there is no return value

Case 2: [ No parameter, With return ]

# use taskorch::{TaskBuildNew as _, TaskBuildOp as _};
let task = 
    (||{3})         // <1> Define the body
        .task()     // <2> Create a task from the given closure.
        .to(2,0);   // <3> Set target;
                    //     the return value will be forwarded to task #2, condition #0.

let task = 
    (||{3})         // <1> ..
        .task();    // <2> ..
                    // <3> `to()` skipped, the return value dropped

Case 3: [ With parameter, No return ]

# use taskorch::TaskBuildNew as _;

let task = 
    (|_:i8|{})      // <1> Define the body, taskid is auto-generated.
        .task();    // <2> Create a task from the given closure.
                    // <3> `to()` skipped, as there is no return value
let task = 
    (|_:i8|{}, 1)   // <1> Define the body, with an explicit taskid.
        .task();    // <2> ..
                    // <3> ..

Case 4: [ With parameter, With return ]

# use taskorch::{TaskBuildNew as _, TaskBuildOp as _};

let task = 
    (|_:i8|{3})     // <1> Define the body, taskid is auto-generated.
        .task();    // <2> Create a task from the given closure.
                    // <3> `to()` skipped, the return value dropped
let task = 
    (|_:i8|{3}, 1)  // <1> Define the body, with an explicit taskid.
        .task();    // <2> ..
                    // <3> ..

let task = 
    (|_:i8|{3})     // <1> Define the body, taskid is auto-generated.
        .task()     // <2> Create a task from the given closure.
        .to(2,0);   // <3> Set target;
                    //     the return value will be forwarded to task #2 and cond #0

let task = 
    (|_:i8|{3}, 1) // <1> Define the body, with an explicit taskid.
        .task()    // <2> ..
        .to(2,0);  // <3> ..

Exit task creation
The only difference here is the use of .exit_task() instead of .task().

⚠️ API NOTE

As this project is currently in early active development, the API is highly unstable and will change in subsequent versions.

Example

use taskorch::{Pool, Queue, TaskBuildNew, TaskBuildOp};
// create 3 tasks and run 
fn main() {
    println!("----- test task orch -----");

    // Step#1. create a Pool
    let mut pool = Pool::new();

    // Step#2. create a queue
    let qid = pool.insert_queue(&Queue::new()).unwrap();
    let submitter = pool.task_submitter(qid).unwrap();

    // Step#3. create tasks

    // an indepent task
    submitter.submit((||println!("free-task:  Hello, 1 2 3 ..")).task());

    // an exit task with ONE str cond
    let id_exit = submitter.submit(
        (|msg:&str|
            println!("exit-task:  received ({msg:?}) and EXIT")

        ).exit_task()
    );

    // another task pass message to exit task
    submitter.submit(
        (||{
            const MSG: &'static str = "exit";
            println!("task 'AA':  I pass [\"{MSG}\"] to exit-task to exit");
            MSG
        }).task().to(id_exit, 0)
    );

    // Step#4. start a thread and run
    pool.spawn_thread_for(qid);

    // Step#5. wait until all finished
    pool.join();
}

For a more complex demo, see the usage example.