close sqlite transactions earlier (#294)

If the database is locked for reading, as it is when step returns ROW,
writes cannot checkpoint the wal leading to ever-increasing wal sizes
and a long delay at shutdown.

By resetting the transaction early, writes become more independent of
reads, memory is released earlier and wal can be checkpointed.
This commit is contained in:
Jacek Sieka 2020-09-21 08:21:47 +02:00 committed by GitHub
parent ea0dbb256e
commit 3ddb498f2a
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 54 additions and 36 deletions

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@ -26,58 +26,76 @@ proc bindBlob(s: ptr sqlite3_stmt, n: int, blob: openarray[byte]): cint =
sqlite3_bind_blob(s, n.cint, unsafeAddr blob[0], blob.len.cint, nil)
proc get*(db: SqStoreRef, key: openarray[byte], onData: DataProc): KvResult[bool] =
checkErr sqlite3_reset(db.getStmt)
checkErr sqlite3_clear_bindings(db.getStmt)
checkErr bindBlob(db.getStmt, 1, key)
let v = sqlite3_step(db.getStmt)
case v
let
v = sqlite3_step(db.getStmt)
res = case v
of SQLITE_ROW:
let
p = cast[ptr UncheckedArray[byte]](sqlite3_column_blob(db.getStmt, 0))
l = sqlite3_column_bytes(db.getStmt, 0)
onData(toOpenArray(p, 0, l-1))
ok(true)
of SQLITE_DONE:
ok(false)
else:
err($sqlite3_errstr(v))
proc put*(db: SqStoreRef, key, value: openarray[byte]): KvResult[void] =
checkErr sqlite3_reset(db.putStmt)
checkErr sqlite3_clear_bindings(db.putStmt)
# release implicit transaction
discard sqlite3_reset(db.getStmt) # same return information as step
discard sqlite3_clear_bindings(db.getStmt) # no errors possible
res
proc put*(db: SqStoreRef, key, value: openarray[byte]): KvResult[void] =
checkErr bindBlob(db.putStmt, 1, key)
checkErr bindBlob(db.putStmt, 2, value)
let res =
if (let v = sqlite3_step(db.putStmt); v != SQLITE_DONE):
err($sqlite3_errstr(v))
else:
ok()
proc contains*(db: SqStoreRef, key: openarray[byte]): KvResult[bool] =
checkErr sqlite3_reset(db.containsStmt)
checkErr sqlite3_clear_bindings(db.containsStmt)
# release implict transaction
discard sqlite3_reset(db.putStmt) # same return information as step
discard sqlite3_clear_bindings(db.putStmt) # no errors possible
res
proc contains*(db: SqStoreRef, key: openarray[byte]): KvResult[bool] =
checkErr bindBlob(db.containsStmt, 1, key)
let v = sqlite3_step(db.containsStmt)
case v
let
v = sqlite3_step(db.containsStmt)
res = case v
of SQLITE_ROW: ok(true)
of SQLITE_DONE: ok(false)
else: err($sqlite3_errstr(v))
proc del*(db: SqStoreRef, key: openarray[byte]): KvResult[void] =
checkErr sqlite3_reset(db.delStmt)
checkErr sqlite3_clear_bindings(db.delStmt)
# release implicit transaction
discard sqlite3_reset(db.containsStmt) # same return information as step
discard sqlite3_clear_bindings(db.containsStmt) # no errors possible
res
proc del*(db: SqStoreRef, key: openarray[byte]): KvResult[void] =
checkErr bindBlob(db.delStmt, 1, key)
let res =
if (let v = sqlite3_step(db.delStmt); v != SQLITE_DONE):
err($sqlite3_errstr(v))
else:
ok()
# release implict transaction
discard sqlite3_reset(db.delStmt) # same return information as step
discard sqlite3_clear_bindings(db.delStmt) # no errors possible
res
proc close*(db: SqStoreRef) =
discard sqlite3_finalize(db.putStmt)
discard sqlite3_finalize(db.getStmt)