February 1998
- OT: Following in the footsteps of JCL Alex Oren
- OT: Following in the footsteps of JCL Nathan Yospe
- OT: Following in the footsteps of JCL Richard Woolcock
- OT: Following in the footsteps of JCL Chris Gray
- OT: Following in the footsteps of JCL coder@ibm.net
- OT: Following in the footsteps of JCL Marc Eyrignoux
- Ada? Andrew C.M. McClintock
- Monthly FAQ posting Koster, Raph
- Monthly FAQ posting Adam Wiggins
- Monthly FAQ posting Ling
- Monthly FAQ Posting Ling
- Monthly FAQ Posting Ling
- Monthly FAQ Posting Ling
- Monthly FAQ Posting Chris Gray
- Monthly FAQ Posting Ling
- Monthly FAQ Posting J C Lawrence
- Monthly FAQ Posting J C Lawrence
- Monthly FAQ Posting Alex Oren
- Monthly FAQ Posting Greg Miller
- Monthly FAQ Posting s001gmu@nova.wright.edu
- Monthly FAQ Posting Ling
- Monthly FAQ Posting Ling
- Monthly FAQ Posting Ling
- Monthly FAQ Posting Ling
- Monthly FAQ Posting Ling
- Monthly FAQ Posting Ling
- Monthly FAQ Posting Ling
- Monthly FAQ Posting Ling
- Monthly FAQ Posting Ling
- Monthly FAQ Posting Ling Lo
- Monthly FAQ Posting Koster, Raph
- Monthly FAQ Posting Ling Lo
- Monthly FAQ Posting Greg Miller
- Monthly FAQ Posting Marian Griffith
- Monthly FAQ Posting Greg Miller
- Monthly FAQ Posting Ling Lo
- Databases Shawn Halpenny
- OT: This is a test coder@ibm.net
- OT: This is a test Alex Oren
- Clients and things [Was: OT: This is a test] Matt Chatterley
- Clients and things [Was: OT: This is a test] coder@ibm.net
- Clients and things [Was: OT: This is a test] Matt Chatterley
- MUD Development Digest Dr. Cat
- DBs and Events Greg Munt
- DBs and Events Nathan Yospe
- DBs and Events Greg Munt
- DBs and Events Nathan Yospe
- DBs and Events Felix A. Croes
Nathan Yospe <yospe@hawaii.edu> wrote:
> On Tue, 10 Feb 1998, Greg Munt wrote:
> :On Tue, 10 Feb 1998, Nathan Yospe wrote:
>
> :> On Tue, 10 Feb 1998, Greg Munt wrote:
>
> :> :Also, any references to caches?
>
> :> Again, can't help you. I've done caches, but not for my mud... and there
> :> is such a broad spectrum of things that qualify as cache. Do you want to
> :> know more about cached in-memory storage for a disk-based DB?
>
> :Yes.
>
> The best sources for this would be J C, any of the Cold people, or, if a
> member of the DGD development team is still around... was that the LPmud
> disk-based project?
There never actually was a DGD development team, unless a team can be
one person. But yes, still here.
All data in DGD is local to objects. Storage in the "swap file" is
allocated in sectors of a certain size; each object in the swap file
takes up at least one sector. This imposes considerable overhead,
since not all sectors will be fully used, but it allows for sector
allocation and deletion to be O(1) operations. Moreover, the sector
size can be set to (a power-of-two portion of) the filesystem sector
size.
When an object is loaded from the swap file, the relevant sectors are
loaded in the sector cache, which is organized as a FIFO queue with
a given maximum size. Whenever a sector is accessed, it is placed at
the tail of the queue. Sectors that drop off at the head are written
to the swap file if necessary, and then discarded from the queue.
From the information in the sectors, the object is loaded in memory.
Only those parts that are actually used are loaded, so most objects
will be partially expanded. Whenever a part is accessed that is
not yet in memory, the relevant sector is found (also a O(1)
operation) and loaded in the sector cache, after which the data
is extracted. Data in sectors is stored in a packed format to
save space.
Objects in memory are linked in a priority queue. Each time an
object is accessed, its priority increases, which may mean that
it changes places with one or more objects in front. Every second
or so, a portion of objects at the head of the queue is swapped
out: the data of the object is written to one or more sectors,
and the in-memory copy of the object is discarded. The portion
of objects that will be swapped out is fixed: for instance, if
the portion of objects swapped out is 1/100th, and there are
N objects in memory, N/100 will be swapped out. This means
that there is always some swapping going on, unless there are
less than 100 objects in memory.
DGD's swap file is not actually a proper database, since it
doesn't contain enough information to restart the server with.
A proper database ("dump file" in DGD's terminology) is created
at a checkpoint: the swapfile is brought in a consistent state
by copying all new or changed objects back to it without actually
discarding them from memory, after which all dirty sectors in
the sector cache are written to the swapfile. Thereafter,
some additional tables are quickly appended at the end of the
swapfile, and some header info is written to the first sector.
The swapfile is then renamed to the dump file, and a new
swapfile is then created by copying sectors from the dump file
at low priority. In this fashion, a checkpoint can be performed
without forking, and without taking the mud down (it may take
only a few seconds, depending on the amount of objects in memory
and the size of the sector cache).
Felix Croes (DGD development team) - DBs and Events Jon A. Lambert
- DBs and Events coder@ibm.net
- DBs and Events Felix A. Croes
- DBs and Events s001gmu@nova.wright.edu
- DBs and Events Jon A. Lambert
- DBs and Events coder@ibm.net
- (subject missing) Ben Greear
- META: Unsubscribed users dur to bounces coder@ibm.net
- META: Unsubscribed users dur to bounces Adam Wiggins
- Source Code Release Greg Munt
- Source Code Release Ben Greear
- Source Code Release Greg Munt
- Source Code Release Ben Greear
- Source Code Release Greg Munt
- Source Code Release Richard Woolcock
- Source Code Release Ben Greear
- Source Code Release Chris Gray
- Source Code Release Greg Munt
- Source Code Release coder@ibm.net
- Source Code Release Richard Woolcock
- Source Code Release Stephen Zepp
- Source Code Release Jon A. Lambert
- Source Code Release Greg Munt
- Source Code Release Jon A. Lambert
- Source Code Release Greg Munt
- Source Code Release Travis Casey
- Source Code Release Jon A. Lambert
- Source Code Release Jon A. Lambert
- [RESEARCH]MUD articles archive (fwd) Greg Munt
- Socket programming (Was: The impact of the web on muds) Jon Leonard
- Socket programming (was: The impact of the web on muds) Vadim Tkachenko
- Socket programming (was: The impact of the web on muds) Richard Woolcock
- byte-code anyone? Chris Gray
- byte-code anyone? Jon Leonard
- byte-code anyone? Chris Gray
- byte-code anyone? Jon Leonard
- byte-code anyone? Chris Gray
- user-centered design (was Clients) Mike Sellers
- OT: Linux g++ Greg Munt
- OT: Linux g++ Ben Greear
- OT: Linux g++ coder@ibm.net
- OT: Linux g++ Shawn Halpenny
- OT: Linux g++ Chris Gray
- OT: Clients Vadim Tkachenko
- OT: Clients Adam Wiggins
- OT: Clients coder@ibm.net
- META: OS wars coder@ibm.net
- META: OS wars Mike Sellers
- Clients Stephen Zepp
- Moore's Law sucks (was: 3D graphics) Brandon J. Rickman
- Moore's Law sucks (was: 3D graphics) Adam Wiggins
- Moore's Law sucks (was: 3D graphics) Chris Gray
- Moore's Law sucks (was: 3D graphics) coder@ibm.net
- Moore's Law sucks (was: 3D graphics) Brandon J. Rickman
- Moore's Law sucks (was: 3D graphics) Mike Sellers
- Moore's Law sucks (was: 3D graphics) Chris Gray
- Moore's Law sucks (was: 3D graphics) Ben Greear
- Moore's Law sucks (was: 3D graphics) Ling
- Moore's Law sucks (was: 3D graphics) Brandon J. Rickman
- Moore's Law sucks (was: 3D graphics) coder@ibm.net
- Moore's Law sucks (was: 3D graphics) Alex Oren
- Version Control (was: DBs and Events) Vadim Tkachenko
- Version Control (was: DBs and Events) coder@ibm.net
- Version Control (was: DBs and Events) Vadim Tkachenko
- Version Control (was: DBs and Events) coder@ibm.net
- Version Control (was: DBs and Events) coder@ibm.net
- Version Control (was: DBs and Events) Jon A. Lambert
- Version Control (was: DBs and Events) s001gmu@nova.wright.edu
- Version Control (was: DBs and Events) Raph & Kristen Koster
- Version Control (was: DBs and Events) coder@ibm.net
- Version Control (was: DBs and Events) Felix A. Croes
- Net protocols for MUDing (was: Moore's Law sucks) Jon Leonard
- Net protocols for MUDing (was: Moore's Law sucks) coder@ibm.net
- Net protocols for MUDing (was: Moore's Law sucks) s001gmu@nova.wright.edu
- Net protocols for MUDing (was: Moore's Law sucks) Vadim Tkachenko
- Net protocols for MUDing (was: Moore's Law sucks) Chris Gray
- Net protocols for MUDing (was: Moore's Law sucks) Caliban Tiresias Darklock
- Net protocols for MUDing (was: Moore's Law sucks) J C Lawrence
- Net protocols for MUDing (was: Moore's Law sucks) J C Lawrence
- Net protocols for MUDing (was: Moore's Law sucks) Adam Wiggins
- Net protocols for MUDing (was: Moore's Law sucks) Chris Gray
- Net protocols for MUDing (was: Moore's Law sucks) Vadim Tkachenko
- Net protocols for MUDing (was: Moore's Law sucks) Chris Gray
- Net protocols for MUDing (was: Moore's Law sucks) Vadim Tkachenko
- Net protocols for MUDing (was: Moore's Law sucks) Chris Gray
- Net protocols for MUDing (was: Moore's Law sucks) Adam Wiggins
- Net protocols for MUDing (was: Moore's Law sucks) Chris Gray
- Net protocols for MUDing (was: Moore's Law sucks) J C Lawrence
- Net protocols for MUDing (was: Moore's Law sucks) Chris Gray
- Net protocols for MUDing (was: Moore's Law sucks) Adam Wiggins
- Net protocols for MUDing (was: Moore's Law sucks) Ben Greear
- Net protocols for MUDing (was: Moore's Law sucks) Adam Wiggins
- Net protocols for MUDing (was: Moore's Law sucks) s001gmu@nova.wright.edu
- Net protocols for MUDing (was: Moore's Law sucks) Jon A. Lambert
- Net protocols for MUDing (was: Moore's Law sucks) J C Lawrence
- VEIL (was: Clients) Brandon Gillespie
- LDMs (large dynamic maps) was Unique items Mike Sellers
- Describing the environment Stephen Zepp
- Describing the environment Richard Woolcock
- Back on the list Niklas Elmqvist
- Back on the list Chris Gray
- Back on the list coder@ibm.net
- Unique items The Eternal City
- Unique items coder@ibm.net
- Position sorting Adam Wiggins
- Position sorting coder@ibm.net
- Unique items coder@ibm.net
- Unique items Nathan F Yospe
- BOOK: Myer's Silverlock coder@ibm.net
- BOOK: Myer's Silverlock Chris Gray
- BOOK: Myer's Silverlock Adam Wiggins
- Dynamic Loading of Modules (was: Back on the list) Niklas Elmqvist
- Dynamic Loading of Modules (was: Back on the list) Vadim Tkachenko
- Dynamic Loading of Modules (was: Back on the list) J C Lawrence
- Dynamic Loading of Modules (was: Back on the list Jon A. Lambert
- Net protocols for MUDing s001gmu@nova.wright.edu
- Net protocols for MUDing Stephen Zepp
- Net protocols for MUDing Chris Gray
- Net protocols for MUDing Adam Wiggins
- Net protocols for MUDing J C Lawrence
- Net protocols for MUDing Shawn Halpenny
- Net protocols for MUDing J C Lawrence
- Net protocols for MUDing Chris Gray
- Dynamic Loading of Modules Niklas Elmqvist
- Senses (was: The MLI Project) s001gmu@nova.wright.edu
- bar-time (was The MLI Project) Mike Sellers
- 3D engines for MUDs (was: The MLI Project) Niklas Elmqvist
- 3D engines for MUDs (was: The MLI Project) J C Lawrence
- 3D engines for MUDs (was: The MLI Project) Michael Hohensee
- 3D engines for MUDs (was: The MLI Project) Miroslav Silovic
- 3D engines for MUDs (was: The MLI Project) Michael Hohensee
- Why not compile java into object code? Ben Greear
- Why not compile java into object code? Cynbe ru Taren
- Why not compile java into object code? Caliban Tiresias Darklock
- Why not compile java into object code? Nathan F Yospe
- Why not compile java into object code? Niklas Elmqvist
- Why not compile java into object code? Ben Greear
- Why not compile java into object code? Jon A. Lambert
- Why not compile java into object code? Travis Casey
- Why not compile java into object code? Chris Gray
- Tutorial: Comments on Hand-crafting a compiler Jon A. Lambert
- Tutorial: Let's build a Compiler! - Part I: Introduction Jon A. Lambert
- Tutorial: Let's build a Compiler! - Part II: Expression Parsing Jon A. Lambert
- Tutorial: Let's build a Compiler! - Part I: Introductio Chris Gray
- Tutorial: Let's build a Compiler! - Part I: Introductio s001gmu@nova.wright.edu
- Tutorial: Let's build a Compiler! - Part I: Introductio coder@ibm.net
- MUD Development Digest Dr. Cat
- MUD Development Digest Koster, Raph
- MUD Development Digest Mike Sellers
- Tutorial: Let's build a Compiler! - Part III: More Expressions Jon A. Lambert
- Tutorial: Let's build a Compiler! - Part IV: Interpreters Jon A. Lambert
- Tutorial: Let's build a Compiler! - Part V: Control Constructs Jon A. Lambert
- Tutorial: Let's build a Compiler! - Part VI: Boolean Expressions Jon A. Lambert
- Tutorial: Let's build a Compiler! - Comments Jon A. Lambert
- Tutorial: Let's build a Compiler! - Part VII: Lexical Scanning Jon A. Lambert
- Tutorial: Let's build a Compiler! - Part VIII: A Little Philosophy Jon A. Lambert
- Tutorial: Let's build a Compiler! - Part IX: A Top View Jon A. Lambert
- Tutorial: Let's build a Compiler! - Part X: Introducing TINY Jon A. Lambert
- Compilers: Toy available for ftp Chris Gray