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diff --git a/info/cmdipc.texinfo b/info/cmdipc.texinfo index d004145..e1007c1 100644 --- a/info/cmdipc.texinfo +++ b/info/cmdipc.texinfo @@ -53,6 +53,14 @@ Texts. A copy of the license is included in the section entitled @menu * Overview:: Brief overview of @command{cmdipc}. * Invoking:: Invocation of @command{cmdipc}. +* Message Queues:: Using message queue +* Semaphores:: Using semaphores +* Shared Memory:: Using shared memory +* Mutexe:: Using mutexe +* Conditions:: Using conditions +* Barriers:: Using barriers +* Shared Locks:: Using shared locks +* Rendezvous:: Using rendezvous * GNU Free Documentation License:: Copying and sharing this manual. @end menu @@ -153,9 +161,246 @@ Print a key derived from an existing file and a project ID. The project ID is a integer between the values 0 and 255, inclusively. The derived key is -probable to be non-unique. +probable to be non-unique. This is a +System V IPC function, and is not +available, and are not necessary, for +POSIX IPC. @end table +The following options are recognised +for interprocess communication units. + +@table @option +@item -n +@itemx --nonblocking +Fail with exit value 2 if the unit +is currently occupied and cannot be +used without waiting. +Not available for shared memory. + +@item -b +@itemx --timeout SECONDS +Not available for shared memory. +Fail with exit value 2 if the unit +is currently occupied and cannot be +used without waiting for at most +@code{SECONDS} seconds. + +@item -m +@itemx --mode OCTAL +Permission bits for the created +unit. +@end table + + + + +@node Message Queues +@chapter Message Queues + +Message queues are primitives and play well +with other programs. Use of message queues +are indicated by the @option{-Q} option. +Message queues is a way to send short messages +between program. + +The key for a System V message queue is an +integer, and the key for a POSIX message queue +is an ASCII string with NUL or slash between +1 character and 254 characters long prefixed +with a slash. + +Recognised options for System V message queues: + +@table @option +@item -s +@itemx --size SIZE +The size of the queue. This is the total +length of all message that can be fit into +the queue before it starts blocking. + +@item -t +@itemx --type TYPE +When sending, a positive integer of the +type associated with the message. + +When receiving, this allows you to +control which types of messages are +received. Zero means that any type is +accepted, a positive value means that +only the indicated type is allowed. +If the value is negative, the first +message of the lowest type that is +at most the absolute value of the +specifed value is received. +@end table + +Recognised options for POSIX message queues: + +@table @option +@item -s +@itemx --size SIZE +The maximum size of messages in the queue. + +@item -z +@itemx --spool SIZE +The size of the queue. This is the number +of messages that can be fit into the queue +before it starts blocking. + +@item -p +@itemx --priority NASTYNESS +The priority allows you to order messages +in the queue. The highest priority message +is received first. By default, messages +are sent at the lowest priority, that is +zero. +@end table + +To receive a message, add the verb +@option{receive}. To send a message, +add the verb @option{send} followed +by the message to send. + + + +@node Semaphores +@chapter Semaphores + +Semaphores are primitives and play well +with other programs. Use of semaphores +are indicated by the @option{-S} option. +Semaphores are primitive concurrency units +that be used for many different things. +Basically, a semaphore is an atomic counter +that is never allowed to go below zero. + +The key for a System V semaphores is an +integer, and the key for a POSIX semaphores +is an ASCII string with NUL or slash between +1 character and 254 characters long prefixed +with a slash. + +The following options are recognised +for semaphores: + +@table @option +@item -i +@itemx --initial VALUE +You can select the value a semaphore should +have when it is created. By default the value +is zero. + +@item -d +@itemx --delta DIFFERENCE +When increasing or decreasing the value of +the semaphore @option{--delta} can be used +to select how much the value should change +with. By default this is 1. Semaphores are +atomic, you are guaranteed to either change +the value exactly as much as specified or +not all at. +@end table + +The verbs @option{v} and @option{p} are +used to increase or decrease the value of +the semaphore, respectively. You can also +set the exact value of the semaphore with +the @option{set} verb which should be +followed directly by the desired value. +To read the current value use the verb +@option{read}. @option{p} will block if +the value of the semaphore would otherwise +go below zero. You can also wait for the +value of the semaphore to reach zero +by using the @option{z} verb. POSIX +semaphores does not have built in support +for @option{z}, therefore when POSIX +semaphores are used, the semaphore will +be used as a spinlock. Keep in mind that +spinlock are often suboptimal and it can +miss that the semaphore's value reaches +zero if it for a very short amount of +time. + + + +@node Shared Memory +@chapter Shared Memory + +Shared memory are primitives and play well +with other programs. Use of shared memory +are indicated by the @option{-M} option. +Shared memory is a form of abstract file +that can be used to store raw data between +programs. It is highly recommended to create +shared memory before any program starts +using it. + +The key for a System V shared memory is an +integer, and the key for a POSIX shared memory +is an ASCII string with NUL or slash between +1 character and 254 characters long prefixed +with a slash. + +The following options are recognised +for shared memory: + +@table @option +@item -s +@itemx --size +When you create a shared memory you +most specify how large, in bytes, the +memory allocation should be. KB, MB, +etc. are not recognised, only bytes. + +@item -l +@itemx --length +When you read shared memory you can +specift how many bytes should be read. +If this is left unspecified the entire +shared memory, starting at the the +selected offset, will be read. + +@item -o +@itemx --offset +When reading and writing shared memory, +you specify how many bytes into the +memory that the reading or writing should +take place. By default the offset is zero. +@end table + +To read the shared memory, use the verb +@option{read}. To write, use the verb +@option{write} followed by the data to +write to the memory. + + + +@node Mutexe +@chapter Mutexe + + + +@node Conditions +@chapter Conditions + + + +@node Barriers +@chapter Barriers + + + +@node Shared Locks +@chapter Shared Locks + + + +@node Rendezvous +@chapter Rendezvous + + @node GNU Free Documentation License @appendix GNU Free Documentation License |