Initial commit

vendor/github.com/jackc/pgconn/stmtcache/stmtcache.go

@@ -0,0 +1,58 @@
+// Package stmtcache is a cache that can be used to implement lazy prepared statements.
+package stmtcache
+
+import (
+	"context"
+
+	"github.com/jackc/pgconn"
+)
+
+const (
+	ModePrepare  = iota // Cache should prepare named statements.
+	ModeDescribe        // Cache should prepare the anonymous prepared statement to only fetch the description of the statement.
+)
+
+// Cache prepares and caches prepared statement descriptions.
+type Cache interface {
+	// Get returns the prepared statement description for sql preparing or describing the sql on the server as needed.
+	Get(ctx context.Context, sql string) (*pgconn.StatementDescription, error)
+
+	// Clear removes all entries in the cache. Any prepared statements will be deallocated from the PostgreSQL session.
+	Clear(ctx context.Context) error
+
+	// StatementErrored informs the cache that the given statement resulted in an error when it
+	// was last used against the database. In some cases, this will cause the cache to maer that
+	// statement as bad. The bad statement will instead be flushed during the next call to Get
+	// that occurs outside of a failed transaction.
+	StatementErrored(sql string, err error)
+
+	// Len returns the number of cached prepared statement descriptions.
+	Len() int
+
+	// Cap returns the maximum number of cached prepared statement descriptions.
+	Cap() int
+
+	// Mode returns the mode of the cache (ModePrepare or ModeDescribe)
+	Mode() int
+}
+
+// New returns the preferred cache implementation for mode and cap. mode is either ModePrepare or ModeDescribe. cap is
+// the maximum size of the cache.
+func New(conn *pgconn.PgConn, mode int, cap int) Cache {
+	mustBeValidMode(mode)
+	mustBeValidCap(cap)
+
+	return NewLRU(conn, mode, cap)
+}
+
+func mustBeValidMode(mode int) {
+	if mode != ModePrepare && mode != ModeDescribe {
+		panic("mode must be ModePrepare or ModeDescribe")
+	}
+}
+
+func mustBeValidCap(cap int) {
+	if cap < 1 {
+		panic("cache must have cap of >= 1")
+	}
+}