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‎corout.fdoc

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In our system, there are four principle operations:
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<ol>
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<li><em>spawn</em> a new fibre</li>
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<li><em>read/em> from a channel</li>
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<li><em>write/em> to a channel</li>
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<li><em>read</em> from a channel</li>
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<li><em>write</em> to a channel</li>
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<li>Commit <em>suicide</em>
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</ol>
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A fibre of control can be in one of four states:
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A fibre of control can be in one of five states:
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<ol>
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<li>Running</em>
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<li>Active (but not running)</li>
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<li>Waiting on I/O</li>
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<li>Waiting on read</li>
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<li>Waiting on write</ii>
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<li>Dead</li>
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</ol>
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In our system, all the resources associated by an <em>unreachable</em> dead
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fibre are automatically reaped by the garbage collector so that in fact
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the fibre is not technically dead because it no longer exists.
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A <em>channel</em> is an object associated with which
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set of fibres all waiting to read or all waiting to write.
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When a write operation is performed on a channel by the running fibre,
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if there are fibres on the channel which are waiting to read
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then one is selected, the data to be written is tranfered from the writer to the reader,
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the fibre is removed from association with the channel,
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and both the running and reader fibre are made active.
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When a read operation is performed on a channel by the running fibre,
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if there are fibres on the channel which are waiting to write
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then one is selected, the data to be written is transfered from the writer to the reader,
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fibre, the fibre is removed from association with the channel,
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and both the running and reader fibre are made active.
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When a fibre commits suicide, it is removed as the running fibre.
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When a new fibre is spawned, both the spawner and spawnee are made active.
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When there is no running fibre, then if an active fibre exists,
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an active fibre is selected and promoted to running state
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and the thread of control begins executing it.
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When there is no running fibre, and no active fibres,
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the whole system terminates. Any fibres waiting on I/O become dead
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The description above is a complete account of the abstract semantics
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known as <em>Communicating Sequential Coroutines</em> or CSC, it is a
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sub system obtain from Tony Hoare's <em>Communicating Sequenmtial Processes</em>
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or CSP, in which concurrency is replaced by an indeterminate total ordering.
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To be precise in CSC all events are totally ordered, however the exact ordering
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is not determinate. This is because a scheduler running the system is free
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to pick any active fibre to run when one is needed.
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In the Felix implementation, a spawned fibre runs immediately
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if the @{spawn_fthread} procedure is used to launch it, or the
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running fibre continues instead, of @{schedule_fthread} is used instead.
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In addition, I/O transfers always result in the reader proceeding,
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to give it a chance to actually fetch the data before the write
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might modify it.
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@h2 next
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stuff
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@felix

‎tmp.html

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@@ -400,17 +400,53 @@ <h1 id='The_concept_of_fibration_h'><img src='/share/src/web/images/minus.gif' i
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In our system, there are four principle operations:
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<ol>
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<li><em>spawn</em> a new fibre</li>
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<li><em>read/em> from a channel</li>
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<li><em>write/em> to a channel</li>
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<li><em>read</em> from a channel</li>
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<li><em>write</em> to a channel</li>
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<li>Commit <em>suicide</em>
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</ol>
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A fibre of control can be in one of four states:
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A fibre of control can be in one of five states:
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<ol>
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<li>Running</em>
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<li>Active (but not running)</li>
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<li>Waiting on I/O</li>
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<li>Waiting on read</li>
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<li>Waiting on write</ii>
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<li>Dead</li>
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</ol>
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In our system, all the resources associated by an <em>unreachable</em> dead
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fibre are automatically reaped by the garbage collector so that in fact
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the fibre is not technically dead because it no longer exists.
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</p><p>A <em>channel</em> is an object associated with which
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set of fibres all waiting to read or all waiting to write.
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</p><p>When a write operation is performed on a channel by the running fibre,
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if there are fibres on the channel which are waiting to read
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then one is selected, the data to be written is tranfered from the writer to the reader,
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the fibre is removed from association with the channel,
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and both the running and reader fibre are made active.
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</p><p>When a read operation is performed on a channel by the running fibre,
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if there are fibres on the channel which are waiting to write
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then one is selected, the data to be written is transfered from the writer to the reader,
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fibre, the fibre is removed from association with the channel,
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and both the running and reader fibre are made active.
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</p><p>When a fibre commits suicide, it is removed as the running fibre.
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</p><p>When a new fibre is spawned, both the spawner and spawnee are made active.
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</p><p>When there is no running fibre, then if an active fibre exists,
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an active fibre is selected and promoted to running state
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and the thread of control begins executing it.
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</p><p>When there is no running fibre, and no active fibres,
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the whole system terminates. Any fibres waiting on I/O become dead
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</p><p>The description above is a complete account of the abstract semantics
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known as <em>Communicating Sequential Coroutines</em> or CSC, it is a
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sub system obtain from Tony Hoare's <em>Communicating Sequenmtial Processes</em>
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or CSP, in which concurrency is replaced by an indeterminate total ordering.
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</p><p>To be precise in CSC all events are totally ordered, however the exact ordering
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is not determinate. This is because a scheduler running the system is free
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to pick any active fibre to run when one is needed.
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</p><p>In the Felix implementation, a spawned fibre runs immediately
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if the <code>spawn_fthread</code> procedure is used to launch it, or the
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running fibre continues instead, of <code>schedule_fthread</code> is used instead.
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</p><p>In addition, I/O transfers always result in the reader proceeding,
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to give it a chance to actually fetch the data before the write
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might modify it.
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</p><h2 id='next_h'><img src='/share/src/web/images/minus.gif' id='next' onclick='toggle(this,"next_d")' alt='+'/> 1.1 next</h2><div id='next_d' style='display:block'>
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<p>stuff
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</p><p><pre class='flxbg'><span class="lineno" id=line1></span> blah

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