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| -rw-r--r-- | info/cmdipc.texinfo | 34 |
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diff --git a/info/cmdipc.texinfo b/info/cmdipc.texinfo index 675c845..5c2cb3a 100644 --- a/info/cmdipc.texinfo +++ b/info/cmdipc.texinfo @@ -186,6 +186,16 @@ is currently occupied and cannot be used without waiting for at most @code{SECONDS} seconds. +For a non primitive unit, the +time to live is reset when it enters +its next state. This could mean +that it could timeout anywhere +between the specifed time and +n times the specifed time when +n is the number of steps in the +action that can block, which with +the current units is at most 3. + @item -m @itemx --mode OCTAL Permission bits for the created @@ -453,6 +463,30 @@ waiting peers, and otherwise @option{wait}. @node Barriers @chapter Barriers +A barrier is a synchronisation primitive +that can be used to make sure the a number +of process continue their work at the same +time and do not fall out of sync with +eachother. A barrier blocks until a select +number of processes have reached it and the +lets all of those processes continue. It +does only have one verb: @option{enter}. + +A ``System V'' barrier is constructed from +two semaphores. A ``POSIX'' barrier is +constructed from three semaphores. This +difference is due to the lack of the +@code{Z} for POSIX semaphores. + +The key for a ``System V'' barrier is +a integer-duo delimited by a full stop. +The key for a ``POSIX'' barrier is a +juxtaposition of three an ASCII strings: +no NUL or slash, between 1 character and +254 characters long, and prefixed with a +slash. + + @node Shared Locks |