<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <link rel="stylesheet" href="style.css" type="text/css"> <meta content="text/html; charset=iso-8859-1" http-equiv="Content-Type"> <link rel="Start" href="index.html"> <link rel="previous" href="Complex.html"> <link rel="next" href="Dbm.html"> <link rel="Up" href="index.html"> <link title="Index of types" rel=Appendix href="index_types.html"> <link title="Index of exceptions" rel=Appendix href="index_exceptions.html"> <link title="Index of values" rel=Appendix href="index_values.html"> <link title="Index of modules" rel=Appendix href="index_modules.html"> <link title="Index of module types" rel=Appendix href="index_module_types.html"> <link title="Arg" rel="Chapter" href="Arg.html"> <link title="Arith_status" rel="Chapter" href="Arith_status.html"> <link title="Array" rel="Chapter" href="Array.html"> <link title="ArrayLabels" rel="Chapter" href="ArrayLabels.html"> <link title="Big_int" rel="Chapter" href="Big_int.html"> <link title="Bigarray" rel="Chapter" href="Bigarray.html"> <link title="Buffer" rel="Chapter" href="Buffer.html"> <link title="Callback" rel="Chapter" href="Callback.html"> <link title="CamlinternalLazy" rel="Chapter" href="CamlinternalLazy.html"> <link title="CamlinternalMod" rel="Chapter" href="CamlinternalMod.html"> <link title="CamlinternalOO" rel="Chapter" href="CamlinternalOO.html"> <link title="Char" rel="Chapter" href="Char.html"> <link title="Complex" rel="Chapter" href="Complex.html"> <link title="Condition" rel="Chapter" href="Condition.html"> <link title="Dbm" rel="Chapter" href="Dbm.html"> <link title="Digest" rel="Chapter" href="Digest.html"> <link title="Dynlink" rel="Chapter" href="Dynlink.html"> <link title="Event" rel="Chapter" href="Event.html"> <link title="Filename" rel="Chapter" href="Filename.html"> <link title="Format" rel="Chapter" href="Format.html"> <link title="Gc" rel="Chapter" href="Gc.html"> <link title="Genlex" rel="Chapter" href="Genlex.html"> <link title="Graphics" rel="Chapter" href="Graphics.html"> <link title="GraphicsX11" rel="Chapter" href="GraphicsX11.html"> <link title="Hashtbl" rel="Chapter" href="Hashtbl.html"> <link title="Int32" rel="Chapter" href="Int32.html"> <link title="Int64" rel="Chapter" href="Int64.html"> <link title="Lazy" rel="Chapter" href="Lazy.html"> <link title="Lexing" rel="Chapter" href="Lexing.html"> <link title="List" rel="Chapter" href="List.html"> <link title="ListLabels" rel="Chapter" href="ListLabels.html"> <link title="Map" rel="Chapter" href="Map.html"> <link title="Marshal" rel="Chapter" href="Marshal.html"> <link title="MoreLabels" rel="Chapter" href="MoreLabels.html"> <link title="Mutex" rel="Chapter" href="Mutex.html"> <link title="Nativeint" rel="Chapter" href="Nativeint.html"> <link title="Num" rel="Chapter" href="Num.html"> <link title="Obj" rel="Chapter" href="Obj.html"> <link title="Oo" rel="Chapter" href="Oo.html"> <link title="Parsing" rel="Chapter" href="Parsing.html"> <link title="Pervasives" rel="Chapter" href="Pervasives.html"> <link title="Printexc" rel="Chapter" href="Printexc.html"> <link title="Printf" rel="Chapter" href="Printf.html"> <link title="Queue" rel="Chapter" href="Queue.html"> <link title="Random" rel="Chapter" href="Random.html"> <link title="Scanf" rel="Chapter" href="Scanf.html"> <link title="Set" rel="Chapter" href="Set.html"> <link title="Sort" rel="Chapter" href="Sort.html"> <link title="Stack" rel="Chapter" href="Stack.html"> <link title="StdLabels" rel="Chapter" href="StdLabels.html"> <link title="Str" rel="Chapter" href="Str.html"> <link title="Stream" rel="Chapter" href="Stream.html"> <link title="String" rel="Chapter" href="String.html"> <link title="StringLabels" rel="Chapter" href="StringLabels.html"> <link title="Sys" rel="Chapter" href="Sys.html"> <link title="Thread" rel="Chapter" href="Thread.html"> <link title="ThreadUnix" rel="Chapter" href="ThreadUnix.html"> <link title="Tk" rel="Chapter" href="Tk.html"> <link title="Unix" rel="Chapter" href="Unix.html"> <link title="UnixLabels" rel="Chapter" href="UnixLabels.html"> <link title="Weak" rel="Chapter" href="Weak.html"><title>Condition</title> </head> <body> <div class="navbar"><a href="Complex.html">Previous</a> <a href="index.html">Up</a> <a href="Dbm.html">Next</a> </div> <center><h1>Module <a href="type_Condition.html">Condition</a></h1></center> <br> <pre><span class="keyword">module</span> Condition: <code class="code"><span class="keyword">sig</span></code> <a href="Condition.html">..</a> <code class="code"><span class="keyword">end</span></code></pre>Condition variables to synchronize between threads. <p> Condition variables are used when one thread wants to wait until another thread has finished doing something: the former thread ``waits'' on the condition variable, the latter thread ``signals'' the condition when it is done. Condition variables should always be protected by a mutex. The typical use is (if <code class="code"><span class="constructor">D</span></code> is a shared data structure, <code class="code">m</code> its mutex, and <code class="code">c</code> is a condition variable): <pre></pre><code class="code"> <span class="constructor">Mutex</span>.lock m;<br> <span class="keyword">while</span> <span class="comment">(* some predicate P over D is not satisfied *)</span> <span class="keyword">do</span><br> <span class="constructor">Condition</span>.wait c m<br> <span class="keyword">done</span>;<br> <span class="comment">(* Modify D *)</span><br> <span class="keyword">if</span> <span class="comment">(* the predicate P over D is now satified *)</span> <span class="keyword">then</span> <span class="constructor">Condition</span>.signal c;<br> <span class="constructor">Mutex</span>.unlock m<br> </code><pre></pre><br> <hr width="100%"> <pre><span id="TYPEt"><span class="keyword">type</span> <code class="type"></code>t</span> </pre> <div class="info"> The type of condition variables.<br> </div> <pre><span id="VALcreate"><span class="keyword">val</span> create</span> : <code class="type">unit -> <a href="Condition.html#TYPEt">t</a></code></pre><div class="info"> Return a new condition variable.<br> </div> <pre><span id="VALwait"><span class="keyword">val</span> wait</span> : <code class="type"><a href="Condition.html#TYPEt">t</a> -> <a href="Mutex.html#TYPEt">Mutex.t</a> -> unit</code></pre><div class="info"> <code class="code">wait c m</code> atomically unlocks the mutex <code class="code">m</code> and suspends the calling process on the condition variable <code class="code">c</code>. The process will restart after the condition variable <code class="code">c</code> has been signalled. The mutex <code class="code">m</code> is locked again before <code class="code">wait</code> returns.<br> </div> <pre><span id="VALsignal"><span class="keyword">val</span> signal</span> : <code class="type"><a href="Condition.html#TYPEt">t</a> -> unit</code></pre><div class="info"> <code class="code">signal c</code> restarts one of the processes waiting on the condition variable <code class="code">c</code>.<br> </div> <pre><span id="VALbroadcast"><span class="keyword">val</span> broadcast</span> : <code class="type"><a href="Condition.html#TYPEt">t</a> -> unit</code></pre><div class="info"> <code class="code">broadcast c</code> restarts all processes waiting on the condition variable <code class="code">c</code>.<br> </div> </body></html>
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