diff --git a/conn.go b/conn.go index 489f32fd..a15c280e 100644 --- a/conn.go +++ b/conn.go @@ -486,7 +486,7 @@ optionLoop: } sd := c.statementCache.Get(sql) if sd == nil { - sd, err = c.Prepare(ctx, stmtcache.NextStatementName(), sql) + sd, err = c.Prepare(ctx, stmtcache.StatementName(sql), sql) if err != nil { return pgconn.CommandTag{}, err } @@ -840,7 +840,7 @@ func (c *Conn) getStatementDescription( } sd = c.statementCache.Get(sql) if sd == nil { - sd, err = c.Prepare(ctx, stmtcache.NextStatementName(), sql) + sd, err = c.Prepare(ctx, stmtcache.StatementName(sql), sql) if err != nil { return nil, err } @@ -1019,7 +1019,7 @@ func (c *Conn) sendBatchQueryExecModeCacheStatement(ctx context.Context, b *Batc bi.sd = distinctNewQueries[idx] } else { sd = &pgconn.StatementDescription{ - Name: stmtcache.NextStatementName(), + Name: stmtcache.StatementName(bi.query), SQL: bi.query, } distinctNewQueriesIdxMap[sd.SQL] = len(distinctNewQueries) diff --git a/internal/stmtcache/lru_cache.go b/internal/stmtcache/lru_cache.go index a25cc8b1..859345fc 100644 --- a/internal/stmtcache/lru_cache.go +++ b/internal/stmtcache/lru_cache.go @@ -34,7 +34,8 @@ func (c *LRUCache) Get(key string) *pgconn.StatementDescription { } -// Put stores sd in the cache. Put panics if sd.SQL is "". Put does nothing if sd.SQL already exists in the cache. +// Put stores sd in the cache. Put panics if sd.SQL is "". Put does nothing if sd.SQL already exists in the cache or +// sd.SQL has been invalidated and HandleInvalidated has not been called yet. func (c *LRUCache) Put(sd *pgconn.StatementDescription) { if sd.SQL == "" { panic("cannot store statement description with empty SQL") @@ -44,6 +45,13 @@ func (c *LRUCache) Put(sd *pgconn.StatementDescription) { return } + // The statement may have been invalidated but not yet handled. Do not readd it to the cache. + for _, invalidSD := range c.invalidStmts { + if invalidSD.SQL == sd.SQL { + return + } + } + if c.l.Len() == c.cap { c.invalidateOldest() } @@ -73,6 +81,8 @@ func (c *LRUCache) InvalidateAll() { c.l = list.New() } +// HandleInvalidated returns a slice of all statement descriptions invalidated since the last call to HandleInvalidated. +// Typically, the caller will then deallocate them. func (c *LRUCache) HandleInvalidated() []*pgconn.StatementDescription { invalidStmts := c.invalidStmts c.invalidStmts = nil diff --git a/internal/stmtcache/stmtcache.go b/internal/stmtcache/stmtcache.go index e1bdcba5..a86755cc 100644 --- a/internal/stmtcache/stmtcache.go +++ b/internal/stmtcache/stmtcache.go @@ -2,18 +2,17 @@ package stmtcache import ( - "strconv" - "sync/atomic" + "crypto/sha256" + "encoding/hex" "github.com/jackc/pgx/v5/pgconn" ) -var stmtCounter int64 - -// NextStatementName returns a statement name that will be unique for the lifetime of the program. -func NextStatementName() string { - n := atomic.AddInt64(&stmtCounter, 1) - return "stmtcache_" + strconv.FormatInt(n, 10) +// StatementName returns a statement name that will be stable for sql across multiple connections and program +// executions. +func StatementName(sql string) string { + digest := sha256.Sum256([]byte(sql)) + return "stmtcache_" + hex.EncodeToString(digest[0:24]) } // Cache caches statement descriptions.