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zhangwenjian
8a1218c404
A file whose name merely contained :memory: or mode=memory was classified as an in-memory database and skipped the locking defaults. Parse the query and match the exact filename forms or a mode=memory parameter.
78 lines
2.5 KiB
Go
78 lines
2.5 KiB
Go
package database
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import (
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"net/url"
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"strings"
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"gorm.io/gorm"
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)
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// sqlitePragmas are the connection parameters a file-backed sqlite database
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// needs to behave under a server that issues concurrent requests. Each one is
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// applied only when the configured source does not already set it.
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//
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// Without them sqlite runs in rollback-journal mode with no busy timeout: a
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// writer blocks every reader and a second writer fails at once with
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// "database is locked", instead of waiting for the first to finish.
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//
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// _busy_timeout wait up to 10s for a lock rather than failing immediately
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// _journal_mode WAL lets readers proceed while a write is in progress
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// _synchronous NORMAL is the pairing WAL is designed for
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// _txlock a transaction takes the write lock when it begins. The
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// default defers it, and a deferred transaction that reads
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// and then writes is refused with SQLITE_BUSY straight away -
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// busy_timeout does not apply to that upgrade.
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var sqlitePragmas = [][2]string{
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{"_busy_timeout", "10000"},
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{"_journal_mode", "WAL"},
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{"_synchronous", "NORMAL"},
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{"_txlock", "immediate"},
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}
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// sqliteDSN returns source with the defaults in sqlitePragmas added.
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// In-memory databases are returned untouched: WAL has no meaning there.
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func sqliteDSN(source string) string {
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if source == "" {
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return source
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}
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path, rawQuery := source, ""
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if i := strings.IndexByte(source, '?'); i >= 0 {
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path, rawQuery = source[:i], source[i+1:]
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}
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q, err := url.ParseQuery(rawQuery)
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if err != nil {
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// Not something to rewrite blind; the driver will report it.
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return source
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}
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if isMemoryDB(path, q) {
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return source
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}
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for _, p := range sqlitePragmas {
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if _, set := q[p[0]]; !set {
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q.Set(p[0], p[1])
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}
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}
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return path + "?" + q.Encode()
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}
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// isMemoryDB reports whether the source names an in-memory database: the exact
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// filename forms sqlite recognises, or a mode=memory parameter. A file that
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// merely has ":memory:" or "mode=memory" somewhere in its name is a file.
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func isMemoryDB(path string, q url.Values) bool {
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switch path {
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case ":memory:", "file::memory:", "file:":
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return true
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}
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return q.Get("mode") == "memory"
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}
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// withSqliteDefaults wraps open so every connection string handed to a sqlite3
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// dialector - the primary and any replicas - carries the defaults above.
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func withSqliteDefaults(driver string, open func(string) gorm.Dialector) func(string) gorm.Dialector {
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if driver != "sqlite3" {
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return open
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}
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return func(dsn string) gorm.Dialector { return open(sqliteDSN(dsn)) }
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}
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