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(declare (uses common))
;;======================================================================
;; attempt to prevent overlapping updates of rollup files by queueing
;; update requests in an sqlite db
;;======================================================================
(define (lock-queue:open-db fname)
(let* ((actualfname (conc fname ".lockdb"))
(dbexists (file-exists? actualfname))
(db (sqlite3:open-database actualfname))
(handler (make-busy-timeout 136000)))
(if dbexists
db
(begin
(sqlite3:execute
db
"CREATE TABLE IF NOT EXISTS queue (
id INTEGER PRIMARY KEY,
test_id INTEGER,
start_time INTEGER,
state TEXT,
CONSTRAINT queue_constraint UNIQUE (test_id));")
(sqlite3:execute
db
"CREATE TABLE IF NOT EXISTS runlocks (
id INTEGER PRIMARY KEY,
test_id INTEGER,
run_lock TEXT,
CONSTRAINT runlock_constraint UNIQUE (run_lock));")))
(sqlite3:set-busy-handler! db handler)
db))
(define (lock-queue:set-state db test-id newstate #!key (remtries 10))
(handle-exceptions
exn
(if (> remtries 0)
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(declare (uses common))
;;======================================================================
;; attempt to prevent overlapping updates of rollup files by queueing
;; update requests in an sqlite db
;;======================================================================
(define (lock-queue:open-db fname #!key (count 10))
(let* ((actualfname (conc fname ".lockdb"))
(dbexists (file-exists? actualfname))
(db (sqlite3:open-database actualfname))
(handler (make-busy-timeout 136000)))
(if dbexists
db
(begin
(handle-exceptions
exn
(begin
(thread-sleep! 10)
(if (> count 0)
(lock-queue:open-db fname count: (- count 1))
db))
(sqlite3:execute
db
"CREATE TABLE IF NOT EXISTS queue (
id INTEGER PRIMARY KEY,
test_id INTEGER,
start_time INTEGER,
state TEXT,
CONSTRAINT queue_constraint UNIQUE (test_id));")
(sqlite3:execute
db
"CREATE TABLE IF NOT EXISTS runlocks (
id INTEGER PRIMARY KEY,
test_id INTEGER,
run_lock TEXT,
CONSTRAINT runlock_constraint UNIQUE (run_lock));"))))
(sqlite3:set-busy-handler! db handler)
db))
(define (lock-queue:set-state db test-id newstate #!key (remtries 10))
(handle-exceptions
exn
(if (> remtries 0)
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;; Actually this should not be needed as mystart cannot be simultaneously less than and test-id same as
(if (not (equal? tid test-id))
(set! res tid)))
db
"SELECT test_id FROM queue WHERE start_time > ?;" mystart)
res)))
(define (lock-queue:get-lock db test-id)
(let ((res #f)
(lckqry (sqlite3:prepare db "SELECT test_id,run_lock FROM runlocks WHERE run_lock='locked';"))
(mklckqry (sqlite3:prepare db "INSERT INTO runlocks (test_id,run_lock) VALUES (?,'locked');")))
(let ((result
(handle-exceptions
exn
#f
(sqlite3:with-transaction
db
(lambda ()
(sqlite3:for-each-row (lambda (tid lockstate)
(set! res (list tid lockstate)))
lckqry)
(if res
(if (equal? (car res) test-id)
#t ;; already have the lock
#f)
(begin
(sqlite3:execute mklckqry test-id)
;; if no error handled then return #t for got the lock
#t)))))))
(sqlite3:finalize! lckqry)
(sqlite3:finalize! mklckqry)
result)))
(define (lock-queue:release-lock fname test-id)
(let ((db (lock-queue:open-db fname)))
(sqlite3:execute db "DELETE FROM runlocks WHERE test_id=?;" test-id)
(sqlite3:finalize! db)))
(define (lock-queue:steal-lock db test-id)
(sqlite3:execute db "DELETE FROM runlocks WHERE run_lock='locked';")
(lock-queue:get-lock db test-it))
;; returns #f if ok to skip the task
;; returns #t if ok to proceed with task
;; otherwise waits
;;
(define (lock-queue:wait-turn fname test-id)
(let ((db (lock-queue:open-db fname))
(mystart (current-seconds)))
(sqlite3:execute
db
"INSERT OR REPLACE INTO queue (test_id,start_time,state) VALUES (?,?,'waiting');"
test-id mystart)
(thread-sleep! 1) ;; give other tests a chance to register
(let ((result
(let loop ((younger-waiting (lock-queue:any-younger? db mystart test-id)))
(if younger-waiting
(begin
;; no need for us to wait. mark in the lock queue db as skipping
(lock-queue:set-state db test-id "skipping")
#f) ;; let the calling process know that nothing needs to be done
(if (lock-queue:get-lock db test-id)
#t
(if (> (- (current-seconds) mystart) 36000) ;; waited too long, steal the lock
(lock-queue:steal-lock db test-id)
(begin
(thread-sleep! 1)
(loop (lock-queue:any-younger? db mystart test-id)))))))))
(sqlite3:finalize! db)
result)))
;; (use trace)
;; (trace lock-queue:get-lock lock-queue:release-lock lock-queue:wait-turn lock-queue:any-younger? lock-queue:set-state)
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;; Actually this should not be needed as mystart cannot be simultaneously less than and test-id same as
(if (not (equal? tid test-id))
(set! res tid)))
db
"SELECT test_id FROM queue WHERE start_time > ?;" mystart)
res)))
(define (lock-queue:get-lock db test-id #!key (count 10))
(let ((res #f)
(lckqry (sqlite3:prepare db "SELECT test_id,run_lock FROM runlocks WHERE run_lock='locked';"))
(mklckqry (sqlite3:prepare db "INSERT INTO runlocks (test_id,run_lock) VALUES (?,'locked');")))
(let ((result
(handle-exceptions
exn
(begin
(thread-sleep! 10)
(if (> count 0)
(lock-queue:get-lock db test-id count: (- count 1)))
#f)
(sqlite3:with-transaction
db
(lambda ()
(sqlite3:for-each-row (lambda (tid lockstate)
(set! res (list tid lockstate)))
lckqry)
(if res
(if (equal? (car res) test-id)
#t ;; already have the lock
#f)
(begin
(sqlite3:execute mklckqry test-id)
;; if no error handled then return #t for got the lock
#t)))))))
(sqlite3:finalize! lckqry)
(sqlite3:finalize! mklckqry)
result)))
(define (lock-queue:release-lock fname test-id #!key (count 10))
(let ((db (lock-queue:open-db fname)))
(handle-exceptions
exn
(begin
(thread-sleep! 10)
(if (> count 0)
(lock-queue:release-lock fname test-id count: (- count 1))
#f))
(sqlite3:execute db "DELETE FROM runlocks WHERE test_id=?;" test-id)
(sqlite3:finalize! db))))
(define (lock-queue:steal-lock db test-id #!key (count 10))
(handle-exceptions
exn
(begin
(thread-sleep! 10)
(if (> count 0)
(lock-queue:steal-lock db test-id count: (- count 1))
#f))
(sqlite3:execute db "DELETE FROM runlocks WHERE run_lock='locked';"))
(lock-queue:get-lock db test-it))
;; returns #f if ok to skip the task
;; returns #t if ok to proceed with task
;; otherwise waits
;;
(define (lock-queue:wait-turn fname test-id #!key (count 10))
(let ((db (lock-queue:open-db fname))
(mystart (current-seconds)))
(handle-exceptions
exn
(begin
(thread-sleep! 10)
(if (> count 0)
(lock-queue:wait-turn fname test-id count: (- count 1))
#f))
(sqlite3:execute
db
"INSERT OR REPLACE INTO queue (test_id,start_time,state) VALUES (?,?,'waiting');"
test-id mystart)
(thread-sleep! 1) ;; give other tests a chance to register
(let ((result
(let loop ((younger-waiting (lock-queue:any-younger? db mystart test-id)))
(if younger-waiting
(begin
;; no need for us to wait. mark in the lock queue db as skipping
(lock-queue:set-state db test-id "skipping")
#f) ;; let the calling process know that nothing needs to be done
(if (lock-queue:get-lock db test-id)
#t
(if (> (- (current-seconds) mystart) 36000) ;; waited too long, steal the lock
(lock-queue:steal-lock db test-id)
(begin
(thread-sleep! 1)
(loop (lock-queue:any-younger? db mystart test-id)))))))))
(sqlite3:finalize! db)
result))))
;; (use trace)
;; (trace lock-queue:get-lock lock-queue:release-lock lock-queue:wait-turn lock-queue:any-younger? lock-queue:set-state)
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