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832b4f9771
When a conn is going to execute a query, the first thing it does is to deallocate any invalidated prepared statements from the statement cache. However, the statements were removed from the cache regardless of whether the deallocation succeeded. This would cause subsequent calls of the same SQL to fail with "prepared statement already exists" error. This problem is easy to trigger by running a query with a context that is already canceled. This commit changes the deallocate invalidated cached statements logic so that the statements are only removed from the cache if the deallocation was successful on the server. https://github.com/jackc/pgx/issues/1847
46 lines
1.6 KiB
Go
46 lines
1.6 KiB
Go
// Package stmtcache is a cache for statement descriptions.
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package stmtcache
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import (
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"crypto/sha256"
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"encoding/hex"
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"github.com/jackc/pgx/v5/pgconn"
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)
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// StatementName returns a statement name that will be stable for sql across multiple connections and program
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// executions.
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func StatementName(sql string) string {
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digest := sha256.Sum256([]byte(sql))
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return "stmtcache_" + hex.EncodeToString(digest[0:24])
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}
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// Cache caches statement descriptions.
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type Cache interface {
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// Get returns the statement description for sql. Returns nil if not found.
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Get(sql string) *pgconn.StatementDescription
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// Put stores sd in the cache. Put panics if sd.SQL is "". Put does nothing if sd.SQL already exists in the cache.
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Put(sd *pgconn.StatementDescription)
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// Invalidate invalidates statement description identified by sql. Does nothing if not found.
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Invalidate(sql string)
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// InvalidateAll invalidates all statement descriptions.
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InvalidateAll()
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// GetInvalidated returns a slice of all statement descriptions invalidated since the last call to RemoveInvalidated.
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GetInvalidated() []*pgconn.StatementDescription
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// RemoveInvalidated removes all invalidated statement descriptions. No other calls to Cache must be made between a
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// call to GetInvalidated and RemoveInvalidated or RemoveInvalidated may remove statement descriptions that were
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// never seen by the call to GetInvalidated.
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RemoveInvalidated()
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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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}
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