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diff --git a/doc/info/cmdipc.texinfo b/doc/info/cmdipc.texinfo new file mode 100644 index 0000000..1ab3c22 --- /dev/null +++ b/doc/info/cmdipc.texinfo @@ -0,0 +1,724 @@ +\input texinfo @c -*-texinfo-*- + +@c %**start of header +@setfilename cmdipc.info +@settitle cmdipc +@afourpaper +@documentencoding UTF-8 +@documentlanguage en +@finalout +@c %**end of header + + +@dircategory Interprocess communication +@direntry +* cmdipc: (cmdipc). System V and POSIX IPC from the command line +@end direntry + + +@copying +Copyright @copyright{} 2014 Mattias Andrée + +@quotation +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with no +Invariant Sections, with no Front-Cover Texts, and with no Back-Cover +Texts. A copy of the license is included in the section entitled +``GNU Free Documentation License''. +@end quotation +@end copying + +@ifnottex +@node Top +@top cmdipc -- System V and POSIX IPC from the command line +@insertcopying +@end ifnottex + +@titlepage +@title cmdipc +@subtitle System V and POSIX IPC from the command line +@author by Mattias Andrée (maandree) + +@page +@c @center `' +@vskip 0pt plus 1filll +@insertcopying +@end titlepage + +@contents + + + +@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 +* Mutexes:: Using mutual exclusives +* 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 + + + +@node Overview +@chapter Overview + +System V and POSIX interprocess communication +from the command line. In addition to the primities +shared memory, message queue and semaphores, this +tool can from these primitives construct mutexes, +conditions, barriers, shared locks and rendezvous. + + + +@node Invoking +@chapter Invoking + +@command{cmdipc} have support for eight types +of interprocess communication units: message +queues, semaphores, shared memory, mutexes +@footnote{Because of the nature of this program, +mutexes are a bit degraded.}, conditions, +barrers, shared locks and rendezvous. These +are constructed from either the three System V +interprocess communication primitives: message +queues, semaphores and shared memory, or their +POSIX variants. The type of interprocess +communication unit to use is selected by the +follow options, to use the POSIX variant rather +than the System V variant add the option +@option{-P} (@option{--posix}). + +@table @option +@item -Q +@itemx --mqueue +Message queue. + +@item -S +@itemx --semaphore +Semaphore. + +@item -M +@itemx --shm +Shared memory. + +@item -X +@itemx --mutex +Mutually exclusive. (Mutex) + +@item -C +@itemx --condition +Condition. + +@item -B +@itemx --barrier +Barrier. + +@item -L +@itemx --shared-lock +Shared lock. + +@item -R +@itemx --rendezvous +Rendezvous. +@end table + +To specify which instance of a unit to use, +specify its key (not ID) with the @option{-k} +(@option{--key}) option. If you do not have +a key, your only option is to create one, but +you can still create a unit with a specified +key. To create a unit use the option @option{-c} +(@option{--create}), this will be successful +even if the key is already in use, in which +case the unit will simply be opened. To fail +if the key is already in use, use the option +@option{-x} (@option{--exclusive}). @option{-x} +can be used with or without @option{-c}, it +is interpretation will does not depend on +@option{-c}, @option{-c} is implied by +@option{-x}. To remove a key, use the option +@option{-r} (@option{--remove}). + +There are two additional options that are +recognised. These cannot be used with any +other optios. + +@table @option +@item -h +@itemx --help +Print a list of all options. + +@item -f +@itemx --ftok PATHNAME ID +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. 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. + +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 +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 Mutexes +@chapter Mutexes + +Mutexes are implemented using semaphores. +Actually, because of inherit limitations, +mutexes are binary semaphores. These are +fairly primitive and should hopefully +interoperate nicely with other programs. +A mutex, with the limitations we have, +is a construct that lets you enter are +guarded state that not be entered again, +even recursively, before it has been left. +Use of mutexes are indicated by the +@option{-X} option. + +The key for a ``System V'' mutex is an +integer, and the key for a ``POSIX'' mutex +is an ASCII string with NUL or slash between +1 character and 254 characters long prefixed +with a slash. + +To enter a guarded state with a mutex, +use the verb @option{enter}. Then leave +it with @option{leave}. + +@* +@cartouche +@example +create: + s := S(1) + +enter: + P(s) + +leave: + V(s) +@end example +@end cartouche + + + +@node Conditions +@chapter Conditions + +A condition is a mutex with support for +signalling. They are implemented using +three semaphores. Just like with mutexes, +you enter and leave guarded states with +conditions. But conditions also allow +to temporarily leave this state and +wait for a signal continue and the +re-enter the guarded state when it is +not occupied. A signal, called +notification, can only be sent from +within a guarded state. +Use of conditions are indicated by the +@option{-C} option. + +The key for a ``System V'' condition is a +integer-trio delimited by full stops. The +key for a ``POSIX'' condition is a +juxtaposition of three ASCII strings: +no NUL or slash, between 1 character and +254 characters long, and prefixed with a +slash. + +To enter a guarded state with a condition, +use the verb @option{enter}. Then leave +it with @option{leave}. The verbs +@option{wait}, @option{notify} and +@option{broadcast} can only be used +after @option{enter} has been used but +before @option{leave}. @option{wait} +temporarily leaves the guarded state +and wait for a notification. A notification +can be sent with @option{notify}. +@option{notify} will send a notify to +exactly one waiting peer. If there is +not peer waiting, the notification will +be stored for the next time @option{wait} +is used. @option{notify} cannot block. +If you want to send a signal to currently +waiting peers you can instead use the +verb @option{broadcast}. Alternatively +you can use @option{notify all} (two +command line arguments) perform a +@option{broadcast} if there are any +waiting peers, and otherwise @option{wait}. + +@* +@cartouche +@example +create: + (s, c, q) := (S(1), S(0), S(0)) + +enter: + P(s) + +leave: + V(s) + +wait: + V(s), V(c), P(q), P(c), P(s) + +notify: + V(q) + +broadcast: + c.value times: + V(q) + +notify all: + max(c.value, 1) times: + V(q) +@end example +@end cartouche + + + +@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}. +The threshold, that is the number of +process that are synchronised, is specified +by the first non-option argument. If +@option{enter} is used, the threshold is +specified before @option{enter}. The +threshold most be specified both at +construction and at usage. +Use of barriers are indicated by the +@option{-B} option. + +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 ASCII strings: +no NUL or slash, between 1 character and +254 characters long, and prefixed with a +slash. + +@* +@cartouche +@example +[sysv] create: + (s, mm c) := (S(threshold), S(1), S(0)) + +[sysv] enter: + P(s), Z(s) + P(m), V(c) + if c.value = threshold: + s.value := threshold + c.value := 0 + V(m) + +[posix] create: + (x, c, q) := (S(1), S(0), S(0)) + +[posix] enter: + P(x), V(c) + if c.value = threshold: + V(q, delta = threshold - 1) + c.value := 0 + V(x) + else: + V(x), P(q) +@end example +@end cartouche + + + +@node Shared Locks +@chapter Shared Locks + +A shared lock is a mutex support for +two types of locks: shared and exclusive. +They are implemented using three semaphores. +Mutexes are can be reduced from shared lock +by only using exclusive locking. Exclusive +locking allows only on program to enter +a guarded state. Shared locks introduce +shared locking works the same why but any +number of programs can be in this state +concurrently. The purpose of the shared +locking is to block exclusive locking. +If you for example are reading and writing +to a file or shared memory, you would +apply an exclusive lock if you want to +be able to modify the content of the +memory and a shared lock if you only +which to be able to read it. This +guarantees both that two processes will +edit the memory at the same time and +cause corruption, and that not process +will modify the memory while another +process is reading it, while allowing +multiple processes to read the memory +at the same time. +Use of shared locks are indicated by the +@option{-L} option. + +The key for a ``System V'' shared lock is +a integer-trio delimited by full stops. +The key for a ``POSIX'' shared lock is a +juxtaposition of three ASCII strings: +no NUL or slash, between 1 character and +254 characters long, and prefixed with a +slash. + +There are four verbs for shared locks: + +@table @option +@item shared lock +Apply shared locking. + +@item exclusive lock +Apply exclusive locking. + +@item shared unlock +Release shared locking. + +@item exclusive unlock +Release exclusive locking. +@* +@end table + +@cartouche +@example +create: + (x, s, m) := (S(1), S(0), S(1)) + +shared lock: + P(m) + if s.value = 0: + P(x) + V(s), V(m) + +exclusive lock: + P(x) + +shared unlock: + P(m), P(s) + if s.value = 0: + V(x) + V(m) + +exclusive unlock: + V(x) +@end example +@end cartouche + + + +@node Rendezvous +@chapter Rendezvous + +A rendezvous is like barrier, except it +is fixed to synchronising two processes. +When two processes meet at a rendezvous +they exchange a message with eachother. +Use of rendezvous are indicated by the +@option{-R} option. @option{-R} inherits +the @option{-s} and @option{-z} options +from @option{-Q}. + +A ``System V'' rendezvous is constructed +from two semaphores and one message queue. +A ``POSIX'' rendezvous is constructed from +three semaphores and one message queue. +This difference is due to POSIX message +queues having priorities instead of types +for messages. + +The key for a ``System V'' rendezvous is +a integer-trio delimited by full stops. +The key for a ``POSIX'' shared lock is a +juxtaposition of four ASCII strings: +no NUL or slash, between 1 character and +254 characters long, and prefixed with a +slash. + +@* +@cartouche +@example +[sysv] create: + (m, i, q) := (S(1), S(0), M()) + +[sysv] enter: + P(m) + if i.value = 0: + V(i), V(m) + send(q, type = 1) + receive(q, type = 2) + else: + P(i), V(m) + receive(q, type = 1) + send(q, type = 2) + +[posix] create: + (m, i, p, q) := (S(1), S(0), S(0), M()) + +[posix] enter: + P(m) + if i.value = 0: + V(i), V(m) + send(q), P(p) + receive(q) + else: + P(i), V(m) + receive(q), V(p) + send(q) +@end example +@end cartouche + + + +@node GNU Free Documentation License +@appendix GNU Free Documentation License +@include fdl.texinfo + +@bye + diff --git a/doc/info/fdl.texinfo b/doc/info/fdl.texinfo new file mode 100644 index 0000000..cb71f05 --- /dev/null +++ b/doc/info/fdl.texinfo @@ -0,0 +1,505 @@ +@c The GNU Free Documentation License. +@center Version 1.3, 3 November 2008 + +@c This file is intended to be included within another document, +@c hence no sectioning command or @node. + +@display +Copyright @copyright{} 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. +@uref{http://fsf.org/} + +Everyone is permitted to copy and distribute verbatim copies +of this license document, but changing it is not allowed. +@end display + +@enumerate 0 +@item +PREAMBLE + +The purpose of this License is to make a manual, textbook, or other +functional and useful document @dfn{free} in the sense of freedom: to +assure everyone the effective freedom to copy and redistribute it, +with or without modifying it, either commercially or noncommercially. +Secondarily, this License preserves for the author and publisher a way +to get credit for their work, while not being considered responsible +for modifications made by others. + +This License is a kind of ``copyleft'', which means that derivative +works of the document must themselves be free in the same sense. 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To do this, add their titles to the +list of Invariant Sections in the Modified Version's license notice. +These titles must be distinct from any other section titles. + +You may add a section Entitled ``Endorsements'', provided it contains +nothing but endorsements of your Modified Version by various +parties---for example, statements of peer review or that the text has +been approved by an organization as the authoritative definition of a +standard. + +You may add a passage of up to five words as a Front-Cover Text, and a +passage of up to 25 words as a Back-Cover Text, to the end of the list +of Cover Texts in the Modified Version. Only one passage of +Front-Cover Text and one of Back-Cover Text may be added by (or +through arrangements made by) any one entity. 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Any attempt +otherwise to copy, modify, sublicense, or distribute it is void, and +will automatically terminate your rights under this License. + +However, if you cease all violation of this License, then your license +from a particular copyright holder is reinstated (a) provisionally, +unless and until the copyright holder explicitly and finally +terminates your license, and (b) permanently, if the copyright holder +fails to notify you of the violation by some reasonable means prior to +60 days after the cessation. + +Moreover, your license from a particular copyright holder is +reinstated permanently if the copyright holder notifies you of the +violation by some reasonable means, this is the first time you have +received notice of violation of this License (for any work) from that +copyright holder, and you cure the violation prior to 30 days after +your receipt of the notice. + +Termination of your rights under this section does not terminate the +licenses of parties who have received copies or rights from you under +this License. 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A copy of the license is included in the section entitled ``GNU + Free Documentation License''. +@end group +@end smallexample + +If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, +replace the ``with@dots{}Texts.''@: line with this: + +@smallexample +@group + with the Invariant Sections being @var{list their titles}, with + the Front-Cover Texts being @var{list}, and with the Back-Cover Texts + being @var{list}. +@end group +@end smallexample + +If you have Invariant Sections without Cover Texts, or some other +combination of the three, merge those two alternatives to suit the +situation. + +If your document contains nontrivial examples of program code, we +recommend releasing these examples in parallel under your choice of +free software license, such as the GNU General Public License, +to permit their use in free software. + +@c Local Variables: +@c ispell-local-pdict: "ispell-dict" +@c End: |