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59 lines
1.9 KiB
59 lines
1.9 KiB
// Package stmtcache is a cache that can be used to implement lazy prepared statements.
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package stmtcache
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import (
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"context"
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"github.com/jackc/pgconn"
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)
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const (
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ModePrepare = iota // Cache should prepare named statements.
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ModeDescribe // Cache should prepare the anonymous prepared statement to only fetch the description of the statement.
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)
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// Cache prepares and caches prepared statement descriptions.
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type Cache interface {
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// Get returns the prepared statement description for sql preparing or describing the sql on the server as needed.
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Get(ctx context.Context, sql string) (*pgconn.StatementDescription, error)
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// Clear removes all entries in the cache. Any prepared statements will be deallocated from the PostgreSQL session.
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Clear(ctx context.Context) error
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// StatementErrored informs the cache that the given statement resulted in an error when it
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// was last used against the database. In some cases, this will cause the cache to maer that
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// statement as bad. The bad statement will instead be flushed during the next call to Get
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// that occurs outside of a failed transaction.
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StatementErrored(sql string, err error)
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// Len returns the number of cached prepared statement descriptions.
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Len() int
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// Cap returns the maximum number of cached prepared statement descriptions.
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Cap() int
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// Mode returns the mode of the cache (ModePrepare or ModeDescribe)
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Mode() int
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}
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// New returns the preferred cache implementation for mode and cap. mode is either ModePrepare or ModeDescribe. cap is
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// the maximum size of the cache.
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func New(conn *pgconn.PgConn, mode int, cap int) Cache {
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mustBeValidMode(mode)
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mustBeValidCap(cap)
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return NewLRU(conn, mode, cap)
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}
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func mustBeValidMode(mode int) {
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if mode != ModePrepare && mode != ModeDescribe {
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panic("mode must be ModePrepare or ModeDescribe")
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}
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}
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func mustBeValidCap(cap int) {
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if cap < 1 {
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panic("cache must have cap of >= 1")
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}
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}
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