diff options
author | Ian Bertolacci <ian.bertolacci@gmail.com> | 2015-07-19 19:59:30 -0700 |
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committer | Ian Bertolacci <ian.bertolacci@gmail.com> | 2015-07-19 19:59:30 -0700 |
commit | 155bf5d0a285de2c4dec4033c8e9c20f6a42072b (patch) | |
tree | ab074e198229a568d4861b21709c16d7deb47aca /chapel.html.markdown | |
parent | bad5266d05485cd61ab1aa0884180ab78738cd9b (diff) |
Added sync, single, and atomic vars.
Diffstat (limited to 'chapel.html.markdown')
-rw-r--r-- | chapel.html.markdown | 78 |
1 files changed, 77 insertions, 1 deletions
diff --git a/chapel.html.markdown b/chapel.html.markdown index 7ac73bbb..4f857775 100644 --- a/chapel.html.markdown +++ b/chapel.html.markdown @@ -757,6 +757,83 @@ timer.clear( ); [ val in myBigArray ] val = 1 / val; // or iterate over indicies [ idx in myBigArray.domain ] myBigArray[idx] = -myBigArray[idx]; + +proc countdown( seconds: int ){ + for i in 1..seconds by -1 { + writeln( i ); + sleep( 1 ); + } +} + +// sync vars have two states: empty and full. +// If you read an empty variable or write a full variable, you are waited +// until the variable is full or empty again +var someSyncVar$: sync int; // varName$ is a convention not a law. +sync { + begin { + writeln( "Waiting to read" ); + var read_sync = someSyncVar$; + writeln( "value is ", read_sync ); + } + + begin { + writeln( "Writing in..." ); + countdown( 3 ); + someSyncVar$ = 123; + } +} + +// single vars can only be written once. A read on an unwritten single results +// in a wait, but when the variable has a value it can be read indefinitely +var someSingleVar$: single int; // varName$ is a convention not a law. +sync { + begin { + writeln( "Waiting to read" ); + for i in 1..5 { + var read_single = someSingleVar$; + writeln( i,"th time around an the value is ", read_single ); + } + } + + begin { + writeln( "Writing in..." ); + countdown( 3 ); + someSingleVar$ = 5; // first and only write ever. + } +} + +// atomic variables can be of type bool, int, uint, and real of any size. +var uranium: atomic int; +uranium.write( 238 ); // atomically write a variable +writeln( uranium.read() ); // atomically read a variable +// operations are described as functions, you could define your own operators. +uranium.sub( 3 ); // atomically subtract a variable +writeln( uranium.read() ); +var replaceWith = 239; +var was = uranium.exchange( replaceWith ); +writeln( "uranium was ", was, " but is now ", replaceWith ); +var isEqualTo = 235; +if uranium.compareExchange( isEqualTo, replaceWith ) { + writeln( "uranium was equal to ", isEqualTo, + " so replaced value with ", replaceWith ); +} else { + writeln( "uranium was not equal to ", isEqualTo, + " value stays the same... whatever it was" ); +} + +sync { + begin { + writeln( "Waiting to for uranium to be ", isEqualTo ); + uranium.waitFor( isEqualTo ); + writeln( "Uranium was set (by someone) to ", isEqualTo ); + } + + begin { + writeln( "Waiting to write uranium to ", isEqualTo ); + countdown( 3 ); + uranium.write( isEqualTo ); + } +} ``` Who is this tutorial for? @@ -771,7 +848,6 @@ Occasionally check back here and on the [Chapel site](http://chapel.cray.com) to ### What this tutorial is lacking: * Modules and standard modules - * Synchronize variables and atomic operations * Multiple Locales (distributed memory system) * ```proc main(){ ... }``` * Records |