[ViewVC] Diff of: cvs/Coro/README

Comparing Coro/README (file contents):
Revision 1.4 by root, Sun Dec 3 21:59:53 2006 UTC vs.
Revision 1.10 by root, Fri Oct 5 10:57:40 2007 UTC

      cede;
 DESCRIPTION
     This module collection manages coroutines. Coroutines are similar to
-    threads but don't run in parallel.
+    threads but don't run in parallel at the same time even on SMP machines.
+    The specific flavor of coroutine used in this module also guarantees you
+    that it will not switch between coroutines unless necessary, at
+    easily-identified points in your program, so locking and parallel access
+    are rarely an issue, making coroutine programming much safer than
+    threads programming.
+    (Perl, however, does not natively support real threads but instead does
+    a very slow and memory-intensive emulation of processes using threads.
+    This is a performance win on Windows machines, and a loss everywhere
+    else).
     In this module, coroutines are defined as "callchain + lexical variables
-    + @_ + $_ + $@ + $^W + C stack), that is, a coroutine has it's own
+    + @_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own
-    callchain, it's own set of lexicals and it's own set of perl's most
+    callchain, its own set of lexicals and its own set of perls most
     important global variables.
     $main
         This coroutine represents the main program.
     $current (or as function: current)
         The current coroutine (the last coroutine switched to). The initial
         value is $main (of course).
         This variable is strictly *read-only*. It is provided for
-        performance reasons. If performance is not essentiel you are
+        performance reasons. If performance is not essential you are
         encouraged to use the "Coro::current" function instead.
     $idle
         A callback that is called whenever the scheduler finds no ready
         coroutines to run. The default implementation prints "FATAL:
     async { ... } [@args...]
         Create a new asynchronous coroutine and return it's coroutine object
         (usually unused). When the sub returns the new coroutine is
         automatically terminated.
-        Calling "exit" in a coroutine will not work correctly, so do not do
+        See the "Coro::State::new" constructor for info about the coroutine
-        that.
+        environment.
-        When the coroutine dies, the program will exit, just as in the main
+        Calling "exit" in a coroutine will do the same as calling exit
-        program.
+        outside the coroutine. Likewise, when the coroutine dies, the
+        program will exit, just as it would in the main program.
            # create a new coroutine that just prints its arguments
            async {
               print "@_\n";
            } 1,2,3,4;
+    async_pool { ... } [@args...]
+        Similar to "async", but uses a coroutine pool, so you should not
+        call terminate or join (although you are allowed to), and you get a
+        coroutine that might have executed other code already (which can be
+        good or bad :).
+        Also, the block is executed in an "eval" context and a warning will
+        be issued in case of an exception instead of terminating the
+        program, as "async" does. As the coroutine is being reused, stuff
+        like "on_destroy" will not work in the expected way, unless you call
+        terminate or cancel, which somehow defeats the purpose of pooling.
+        The priority will be reset to 0 after each job, tracing will be
+        disabled, the description will be reset and the default output
+        filehandle gets restored, so you can change alkl these. Otherwise
+        the coroutine will be re-used "as-is": most notably if you change
+        other per-coroutine global stuff such as $/ you need to revert that
+        change, which is most simply done by using local as in " local $/ ".
+        The pool size is limited to 8 idle coroutines (this can be adjusted
+        by changing $Coro::POOL_SIZE), and there can be as many non-idle
+        coros as required.
+        If you are concerned about pooled coroutines growing a lot because a
+        single "async_pool" used a lot of stackspace you can e.g.
+        "async_pool { terminate }" once per second or so to slowly replenish
+        the pool. In addition to that, when the stacks used by a handler
+        grows larger than 16kb (adjustable with $Coro::POOL_RSS) it will
+        also exit.
     schedule
         Calls the scheduler. Please note that the current coroutine will not
         be put into the ready queue, so calling this function usually means
         you will never be called again unless something else (e.g. an event
                  # wake up sleeping coroutine
                  $current->ready;
                  undef $current;
               };
-              # call schedule until event occured.
+              # call schedule until event occurred.
               # in case we are woken up for other reasons
               # (current still defined), loop.
               Coro::schedule while $current;
            }
         "Cede" to other coroutines. This function puts the current coroutine
         into the ready queue and calls "schedule", which has the effect of
         giving up the current "timeslice" to other coroutines of the same or
         higher priority.
+        Returns true if at least one coroutine switch has happened.
+    Coro::cede_notself
+        Works like cede, but is not exported by default and will cede to any
+        coroutine, regardless of priority, once.
+        Returns true if at least one coroutine switch has happened.
     terminate [arg...]
         Terminates the current coroutine with the given status values (see
         cancel).
+    killall
+        Kills/terminates/cancels all coroutines except the currently running
+        one. This is useful after a fork, either in the child or the parent,
+        as usually only one of them should inherit the running coroutines.
     # dynamic methods
   COROUTINE METHODS
     These are the methods you can call on coroutine objects.
         Create a new coroutine and return it. When the sub returns the
         coroutine automatically terminates as if "terminate" with the
         returned values were called. To make the coroutine run you must
         first put it into the ready queue by calling the ready method.
-        Calling "exit" in a coroutine will not work correctly, so do not do
+        See "async" and "Coro::State::new" for additional info about the
-        that.
+        coroutine environment.
     $success = $coroutine->ready
         Put the given coroutine into the ready queue (according to it's
         priority) and return true. If the coroutine is already in the ready
         queue, do nothing and return false.
     $is_ready = $coroutine->is_ready
         Return wether the coroutine is currently the ready queue or not,
     $coroutine->cancel (arg...)
         Terminates the given coroutine and makes it return the given
-        arguments as status (default: the empty list).
+        arguments as status (default: the empty list). Never returns if the
+        coroutine is the current coroutine.
     $coroutine->join
         Wait until the coroutine terminates and return any values given to
-        the "terminate" or "cancel" functions. "join" can be called multiple
+        the "terminate" or "cancel" functions. "join" can be called
-        times from multiple coroutine.
+        concurrently from multiple coroutines.
+    $coroutine->on_destroy (\&cb)
+        Registers a callback that is called when this coroutine gets
+        destroyed, but before it is joined. The callback gets passed the
+        terminate arguments, if any.
     $oldprio = $coroutine->prio ($newprio)
         Sets (or gets, if the argument is missing) the priority of the
         coroutine. Higher priority coroutines get run before lower priority
         coroutines. Priorities are small signed integers (currently -4 ..
     $olddesc = $coroutine->desc ($newdesc)
         Sets (or gets in case the argument is missing) the description for
         this coroutine. This is just a free-form string you can associate
         with a coroutine.
-  UTILITY FUNCTIONS
+        This method simply sets the "$coroutine->{desc}" member to the given
+        string. You can modify this member directly if you wish.
+  GLOBAL FUNCTIONS
+    Coro::nready
+        Returns the number of coroutines that are currently in the ready
+        state, i.e. that can be switched to. The value 0 means that the only
+        runnable coroutine is the currently running one, so "cede" would
+        have no effect, and "schedule" would cause a deadlock unless there
+        is an idle handler that wakes up some coroutines.
+    my $guard = Coro::guard { ... }
+        This creates and returns a guard object. Nothing happens until the
+        object gets destroyed, in which case the codeblock given as argument
+        will be executed. This is useful to free locks or other resources in
+        case of a runtime error or when the coroutine gets canceled, as in
+        both cases the guard block will be executed. The guard object
+        supports only one method, "->cancel", which will keep the codeblock
+        from being executed.
+        Example: set some flag and clear it again when the coroutine gets
+        canceled or the function returns:
+           sub do_something {
+              my $guard = Coro::guard { $busy = 0 };
+              $busy = 1;
+              # do something that requires $busy to be true
+           }
     unblock_sub { ... }
         This utility function takes a BLOCK or code reference and "unblocks"
         it, returning the new coderef. This means that the new coderef will
         return immediately without blocking, returning nothing, while the
         original code ref will be called (with parameters) from within its
         own coroutine.
-        The reason this fucntion exists is that many event libraries (such
+        The reason this function exists is that many event libraries (such
         as the venerable Event module) are not coroutine-safe (a weaker form
         of thread-safety). This means you must not block within event
         callbacks, otherwise you might suffer from crashes or worse.
         This function allows your callbacks to block by executing them in
 BUGS/LIMITATIONS
      - you must make very sure that no coro is still active on global
        destruction. very bad things might happen otherwise (usually segfaults).
      - this module is not thread-safe. You should only ever use this module
-       from the same thread (this requirement might be losened in the future
+       from the same thread (this requirement might be loosened in the future
        to allow per-thread schedulers, but Coro::State does not yet allow
        this).
 SEE ALSO
-    Support/Utility: Coro::Cont, Coro::Specific, Coro::State, Coro::Util.
+    Support/Utility: Coro::Specific, Coro::State, Coro::Util.
     Locking/IPC: Coro::Signal, Coro::Channel, Coro::Semaphore,
     Coro::SemaphoreSet, Coro::RWLock.
     Event/IO: Coro::Timer, Coro::Event, Coro::Handle, Coro::Socket,

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing Coro/README (file contents): Revision 1.4 by root, Sun Dec 3 21:59:53 2006 UTC vs. Revision 1.10 by root, Fri Oct 5 10:57:40 2007 UTC

Diff Legend

Comparing Coro/README (file contents):
Revision 1.4 by root, Sun Dec 3 21:59:53 2006 UTC vs.
Revision 1.10 by root, Fri Oct 5 10:57:40 2007 UTC