--- /dev/null
+
+
+OVERALL STATES, defining interaction with innd:
+
+ START
+ |
+ ,-->--. check F, D
+ | | |
+ | | |
+ | | <----------------<---------------------------------'|
+ | | F exists |
+ | | D ENOENT |
+ | | duct opens F |
+ | V |
+ | Normal |
+ | F: innd writing, duct reading |
+ | D: ENOENT |
+ | | |
+ | | duct decides time to flush |
+ | | duct makes hardlink |
+ | | |
+ | V <------------------------'|
+ | Hardlinked F==D |
+ | F == D: innd writing, duct reading both exist |
+ ^ | |
+ | | duct unlinks F |
+ | | <-----------<-------------<--'|
+ | | open D F ENOENT |
+ | | if exists |
+ | | |
+ | V <---------------------. |
+ | Moved | |
+ | F: ENOENT | |
+ | D: innd writing, duct reading; or ENOENT | |
+ | | | |
+ | | duct requests flush of feed | |
+ | | (others can too, harmlessly) | |
+ | V | |
+ | Flushing | |
+ | F: ENOENT | |
+ | D: innd flushing, duct; or ENOENT | |
+ | | | |
+ | | inndcomm flush fails | |
+ | |`-------------------------->------------------' |
+ | | |
+ | | inndcomm reports no such site |
+ | |`---------------------------------------------------- | -.
+ | | | |
+ | | innd finishes writing D, creates F | |
+ | | inndcomm reports flush successful | |
+ | | | |
+ | V | |
+ | Separated <----------------' |
+ | F: innd writing F!=D /
+ | D: duct reading; or ENOENT both exist /
+ | | /
+ | | duct gets to the end of D /
+ | | duct opens F too /
+ | V /
+ | Finishing /
+ | F: innd writing, duct reading |
+ | D: duct finishing V
+ | | Dropping
+ | | duct finishes processing D F: ENOENT
+ | V duct unlinks D D: duct reading
+ | | |
+ `--<--' | duct finishes
+ | processing D
+ | duct unlinks D
+ | duct exits
+ V
+ Dropped
+ F: ENOENT
+ D: ENOENT
+ duct not running
+
+ "duct reading" means innduct is reading the file but also
+ overwriting processed tokens.
+
+\f
+
+We implement this as follows:
+
+ .=======.
+ ||START||
+ `======='
+ |
+ | open F
+ |
+ | F ENOENT
+ |`---------------------------------------------------.
+ F OPEN OK | |
+ |`---------------- - - - |
+ D ENOENT | D EXISTS see OVERALL STATES diagram |
+ | for full startup logic |
+ ,--------->| |
+ | V |
+ | ============ try to |
+ | NORMAL open D |
+ | [Normal] |
+ | main F tail |
+ | ============ V
+ | | |
+ | | F IS SO BIG WE SHOULD FLUSH, OR TIMEOUT |
+ ^ | hardlink F to D |
+ | [Hardlinked] |
+ | | unlink F |
+ | | our handle onto F is now onto D |
+ | [Moved] |
+ | | |
+ | |<-------------------<---------------------<---------+
+ | | |
+ | | spawn inndcomm flush |
+ | V |
+ | ================== |
+ | FLUSHING[-ABSENT] |
+ | [Flushing] |
+ | main D tail/none |
+ | ================== |
+ | | |
+ | | INNDCOMM FLUSH FAILS ^
+ | |`----------------------->----------. |
+ | | | |
+ | | NO SUCH SITE V |
+ ^ |`--------------->----. ==================== |
+ | | \ FLUSHFAILED[-ABSENT] |
+ | | \ [Moved] |
+ | | FLUSH OK \ main D tail/none |
+ | | open F \ ==================== |
+ | | \ | |
+ | | \ | TIME TO RETRY |
+ | |`------->----. ,---<---'\ `----------------'
+ | | D NONE | | D NONE `----.
+ | V | | V
+ | ============= V V ============
+ | SEPARATED-1 | | DROPPING-1
+ | flsh->rd!=0 | | flsh->rd!=0
+ | [Separated] | | [Dropping]
+ | main F idle | | main none
+ | flsh D tail | | flsh D tail
+ | ============= | | ============
+ | | | | install |
+ ^ | EOF ON D | | defer | EOF ON D
+ | V | | V
+ | =============== | | ===============
+ | SEPARATED-2 | | DROPPING-2
+ | flsh->rd==0 | V flsh->rd==0
+ | [Finishing] | | [Dropping]
+ | main F tail | `. main none
+ | flsh D closed | `. flsh D closed
+ | =============== V `. ===============
+ | | `. |
+ | | ALL D PROCESSED `. | ALL D PROCESSED
+ | V install defer as backlog `. | install defer
+ ^ | close D `. | close D
+ | | unlink D `. | unlink D
+ | | | |
+ | | V V
+ `----------' ==============
+ DROPPED
+ [Dropped]
+ main none
+ flsh none
+ some backlog
+ ==============
+ |
+ | ALL BACKLOG DONE
+ |
+ | unlink lock
+ | exit
+ V
+ ==========
+ (ESRCH)
+ [Droppped]
+ ==========
+
+
+rune for printing diagrams:
+ a2ps -R -B -ops README.states
~ian / inn-innduct.git / blobdiff