17.1.1 Thread API

Bigloo uses a set of primitive functions and methods to create, run and handle thread. For the sake of standardization the name and semantic of SRFI-18 has been used. This section presents only the mandatory functions to program with threads in Bigloo.

The most important difference with SRFI-18, is the missing of the function make-thread, which is not available for all libraries, as it can be hard to predict the type of thread which will be created if several thread libraries are used simultaneously. As threads are regular Bigloo objects, they can be created using the instantiate syntax. See the Threads and Posix Threads specific sections for more details about thread creation and examples.

The examples given in this section use a generic syntax with instantiate::thread, to run the examples, you will have to put them in a function in a module (see Section Modules, and import one of the libraries using library module declaration.

SRFI-18 function: current-thread

Returns the current thread.

SRFI-18 function: thread? obj

Returns #t if obj is a thread, otherwise returns #f.

SRFI-18 function: thread-name thread

Returns the name of the thread.

SRFI-18 function: thread-specific thread

SRFI-18 function: thread-specific-set! thread obj

Returns and sets value in the specific field of the thread. If no value has been set, thread-specific returns an unspecified value.

(let ((t (instantiate::thread
          (body (lambda ()
                   (print (thread-specific (current-thread))))))))
   (thread-specific-set! t 'foo)
   (thread-start! t)) -| foo

Bigloo function: thread-cleanup thread

Bigloo function: thread-cleanup-set! thread fun

Associates a cleanup function to a thread. The cleanup function is called with the thread itself. The cleanup function is executed in a context where current-thread is the thread owning the cleanup function.

(let ((t (instantiate::thread (body (lambda () 'done) 'foo))))
   (thread-cleanup-set! t (lambda (v) (print (thread-name (current-thread))
					     ", exit value: " v)))
   (thread-start! t)) -| foo, exit value: done

Bigloo function: thread-parameter ident

Bigloo function: thread-parameter-set! ident value

Returns the value of the parameter ident in the current thread. If no value is bound to this parameter, #f is returned.

A thread parameter is implemented by a chunk of memory specific to each thread. All threads are created with an empty set of parameters.

The next functions have different behaviors depending in the library used, more details will be given in the specific sections below.

SRFI-18 function: thread-start! thread [args]

Bigloo function: thread-start-joinable! thread

SRFI-18 function: thread-join! thread [timeout]

SRFI-18 function: thread-terminate! thread

SRFI-18 function: thread-yield!

SRFI-18 function: thread-sleep! timeout

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