April 1997
- From out of the shadows... Dan Mazeau
- Introduction Shawn Halpenny
- Introduction Nathan Yospe
- Introduction Chris Gray
- Introduction coder@ibm.net
- Introduction S001GMU@nova.wright.edu
- Introduction Jeff Kesselman
- Introduction Chris Gray
- Introduction Mik Clarke
- Introduction Caliban Tiresias Darklock
- Introduction Mik Clarke
- Introduction Caliban Tiresias Darklock
- Introduction J C Lawrence
- Introduction Elia Morling
- Event-driven? Michael Hohensee
- Event-driven? Nathan Yospe
- Event-driven? coder@ibm.net
- Event-driven? Jon A. Lambert
- Event-driven? Adam Wiggins
- Event-driven? Shawn Halpenny
- Event-driven? Chris Gray
- Event-driven? coder@ibm.net
- (subject missing) Dan Mazeau
- A late introduction Jon A. Lambert
- Re-Introduction S001GMU@nova.wright.edu
- New guy Walter Goodwin
- New guy coder@ibm.net
- Socket Stuff Shawn Halpenny
- database stuff Chris Gray
- So in an event-driven server, how do you ... Michael Hohensee
- So in an event-driven server, how do you ... Nathan Yospe
- So in an event-driven server, how do you ... S001GMU@nova.wright.edu
- So in an event-driven server, how do you ... Chris Gray
- So in an event-driven server, how do you ... clawrenc@xsvr1.cup.hp.com
- So in an event-driven server, how do you ... clawrenc@cup.hp.com
- Off on the languages tangent! Chris Gray
- Yet Another Introduction Reed D. Copsey, Jr.
- Yet Another Introduction Nathan Yospe
- Yet Another Introduction clawrenc@cup.hp.com
- Yet Another Introduction clawrenc@cup.hp.com
- Yet Another Introduction Adam Wiggins
- Yet Another Introduction Dmitri Kondratiev
- self-intro: Cynbe Cynbe ru Taren
- Unique id's Chris Gray
- Unique id's clawrenc@cup.hp.com
- Unique id's Jon A. Lambert
- Unique id's coder@ibm.net
- Unique id's Jon A. Lambert
- Unique id's coder@ibm.net
- Unique id's Jeff Kesselman
- Unique id's clawrenc@cup.hp.com
- Unique id's Jon A. Lambert
- Dupes are my fault (again) coder@ibm.net
- six degrees of submission ... er, compilation. Cynbe ru Taren
- six degrees of submission ... er, compilation. Jeff Kesselman
- Java as a mudserver language Cynbe ru Taren
- Java as a mudserver language Jeff Kesselman
- Execution Chris Gray
- Using system time for ObjectIDs clawrenc@cup.hp.com
- short absence Chris Gray
- short absence coder@ibm.net
- Hello! Ross Nicoll
- Ho hum (clarifiyign AI terms) Jeff Kesselman
- Ho hum Ling
- Fw: Just a bit of musing Travis Casey
- Risk Assessment -- was (Ho hum) Jon A. Lambert
- Who is Steward and what can he do for me? Jon A. Lambert
- Who is Steward and what can he do for me? clawrenc@cup.hp.com
- Who is Steward and what can he do for me? Chris Gray
- project management (or coding, kings, and other things) Jon A. Lambert
- Threads and Sockets (Was Ho hum) S001GMU@nova.wright.edu
- Threads and Sockets (Was Ho hum) Jeff Kesselman
- Threads and Sockets (Was Ho hum) S001GMU@nova.wright.edu
- Threads and Sockets (Was Ho hum) clawrenc@cup.hp.com
- Threads and Sockets (Was Ho hum) Chris Gray
- Strings & Memory Usage Greg Munt
- Strings & Memory Usage clawrenc@cup.hp.com
- Strings & Memory Usage Jeff Kesselman
- Strings & Memory Usage Shawn Halpenny
- Strings & Memory Usage ashen
- Strings & Memory Usage Chris Gray
- Steward coder@ibm.net
- r.g.m.* - worthwhile thread Nathan Yospe
- r.g.m.* - worthwhile thread clawrenc@cup.hp.com
- r.g.m.* - worthwhile thread Jeff Kesselman
- r.g.m.* - worthwhile thread Chris Gray
- (fwd) A Mud Protocol (MUD Markup Language) coder@ibm.net
- Ho hum (Sockets) Ling
- Steward and other painful friends coder@ibm.net
- A Combat System (please critique!) S001GMU@nova.wright.edu
- Your Message To mud-dev Jon A. Lambert
- I'm back Chris Gray
- Changes to the list coder@ibm.net
- Oops coder@ibm.net
- Verb binding Chris Gray
- Verb binding clawrenc@cup.hp.com
- Verb binding ashen
- Verb binding Chris Gray
- Verb binding Adam Wiggins
- Verb binding clawrenc@cup.hp.com
- Verb binding S001GMU@nova.wright.edu
- Verb binding Shawn Halpenny
- Verb binding Chris Gray
- Verb binding clawrenc@cup.hp.com
- Verb binding Chris Gray
- Why have a combat state? Jeff Kesselman
- Why have a combat state? clawrenc@cup.hp.com
- Introduction Jamie Norrish
- Introduction S001GMU@nova.wright.edu
- Introduction clawrenc@cup.hp.com
- Introduction Jeff Kesselman
- Introduction clawrenc@cup.hp.com
- Introduction Chris Gray
- Introduction Travis Casey
- Introduction Jeff Kesselman
- Introduction scherecwich@angelfire.com
- Introduction Jon A. Lambert
- Introduction Chris Gray
- (fwd) Issues from the digests and Wout's list Raz
- (fwd) Issues from the digests and Wout's list Chris Gray
- (fwd) Issues from the digests and Wout's list clawrenc@cup.hp.com
- (fwd) Issues from the digests and Wout's list Raz
- (fwd) Issues from the digests and Wout's list Chris Gray
- (fwd) Issues from the digests and Wout's list clawrenc@cup.hp.com
- (fwd) Issues from the digests and Wout's list Chris Gray
- (fwd) Issues from the digests and Wout's list clawrenc@cup.hp.com
- (fwd) Issues from the digests and Wout's list Oliver Jowett
- (fwd) Issues from the digests and Wout's list Chris Gray
- (fwd) Issues from the digests and Wout's list clawrenc@cup.hp.com
- (fwd) Issues from the digests and Wout's list Raz
- (fwd) Issues from the digests and Wout's list Miroslav Silovic
- (fwd) Issues from the digests and Wout's list clawrenc@cup.hp.com
- (fwd) Issues from the digests and Wout's list Adam Wiggins
- (fwd) Issues from the digests and Wout's list clawrenc@cup.hp.com
- (fwd) Issues from the digests and Wout's list Miroslav Silovic
- (fwd) Issues from the digests and Wout's list clawrenc@cup.hp.com
- (fwd) Issues from the digests and Wout's list Raz
- (fwd) Issues from the digests and Wout's list clawrenc@cup.hp.com
- (fwd) Issues from the digests and Wout's list clawrenc@cup.hp.com
- Me Raz
- Sendmail changes coder@ibm.net
- Reposts Adam Wiggins
- Semaphores, Mutices, fd_sets Greg Munt
- Semaphores, Mutices, fd_sets Jeff Kesselman
- Semaphores, Mutices, fd_sets clawrenc@cup.hp.com
In <Pine.LNX.3.91.970426164344.1764M-100000@uni-corn.demon.co.uk>, on
04/26/97
at 09:08 AM, Greg Munt <greg@uni-corn.demon.co.uk> said:
>I've seen the words 'Semaphore' and 'Mutex' thrown about in RGMA
>lately. But I have no idea what they are. Would anyone be able to
>help me out?
They are more or less identical in practice, but the basics:
A semaphore is an item which can atomically be queried for a
state, and if not present that state set.
The standard implementation here allows several basic manipulations on
a semaphore, with the most standard probably being:
Check the state of the semaphore.
If the sempahore is set, block until it is unset and then try again.
If it is not set, set it, and continue.
This is commonly called "locking" the semaphore.
Processes that are blocked on the semaphore as said to be
"waiting" on it.
(Of course with the above all done atomically)
And:
Unset the semaphore I'm currently holding set.
This is commonly called "unlocking" or "releasing".
And:
Get the current set/unset state of the semaphore.
Inside this very general scope there are a lot of variations on
semaphores. Unix has a particularly nasty variation as it explicitly
allows arrays of semaphores to be manipulated as above (lock, release
test) in one atomic operation, as well as having each individual
semaphore able to have any positive or negative int value (with all
the test/set etc APIs generalised for that). <<Truth to tell, Unix
semaphores are even nastier than that>>
A mutex is just a variation on a semaphore. Mutex stands for "mutual
exclusion". Fairly simply its a semaphore type best that ensures that
only one user has access to a given resource at a time. In Unix'es
case a mutex is just a standard semaphore with a bunch of wrappers
about it to make the API simpler/cleaner.
What OS do you want to know about semaphores and mutex'es for?
>Also, an fd_set holds FD_SETSIZE file descriptors. Is it true that a
>theroretically infinite number of FDs can be opened by the server,
>and that I can handle > FD_SETSIZE connections by having some kind
>of linked list of fd_sets?
Almost always: No. The exceptions are so rare and so limited as to be
ignorable (certain classes of list based OS'es etc).
Typically the base OS or OS kernel will have a built in limit of how
many files can be open in the system at a time. Many OS'es will have
a similar (smaller) limit for processes, but its often the same.
Per-process, or per-account permissions may reduce that number even
more.
Thus the XXX operating system can have up to, uhh, 9 files open at a
time. However a single process can only have up to 8 files open at an
instant (one handle already being occupied with application opening
the file) However, the great user Bubba, running the process may have
an account maximum of 3 files open at any one instant...
--
J C Lawrence Internet: claw@null.net
(Contractor) Internet: coder@ibm.net
---------------(*) Internet: clawrenc@cup.hp.com
...Honorary Member Clan McFUD -- Teamer's Avenging Monolith...
- MUD Design Digest V1 #55 coder@ibm.net
- Me Raz
- Magnetic Scrolls' magical parser Greg Munt
- Magnetic Scrolls' magical parser clawrenc@cup.hp.com
- Magnetic Scrolls' magical parser Adam Wiggins
- Magnetic Scrolls' magical parser Nathan Yospe
- Magnetic Scrolls' magical parser Chris Gray
- Magnetic Scrolls' magical parser Ling
- Magnetic Scrolls' magical parser Chris Gray
- Magnetic Scrolls' magical parser Shawn Halpenny
- Reposts Jeff Kesselman
- Email change Alex Oren
- SUBSCRIBE Alex Oren
- (fwd) Death in Muds -(also Birth, Imprisonment, Aging, and skill development) coder@ibm.net
- fd_set limitations Greg Munt
- parsing Chris Gray