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+/*-------------------------------------------------------------------------
+ *
+ * lockdefs.h
+ * Frontend exposed parts of postgres' low level lock mechanism
+ *
+ * The split between lockdefs.h and lock.h is not very principled. This file
+ * contains definition that have to (indirectly) be available when included by
+ * FRONTEND code.
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/lockdefs.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef LOCKDEFS_H_
+#define LOCKDEFS_H_
+
+/*
+ * LOCKMODE is an integer (1..N) indicating a lock type. LOCKMASK is a bit
+ * mask indicating a set of held or requested lock types (the bit 1<<mode
+ * corresponds to a particular lock mode).
+ */
+typedef int LOCKMASK;
+typedef int LOCKMODE;
+
+/*
+ * These are the valid values of type LOCKMODE for all the standard lock
+ * methods (both DEFAULT and USER).
+ */
+
+/* NoLock is not a lock mode, but a flag value meaning "don't get a lock" */
+#define NoLock 0
+
+#define AccessShareLock 1 /* SELECT */
+#define RowShareLock 2 /* SELECT FOR UPDATE/FOR SHARE */
+#define RowExclusiveLock 3 /* INSERT, UPDATE, DELETE */
+#define ShareUpdateExclusiveLock 4 /* VACUUM (non-FULL),ANALYZE, CREATE INDEX
+ * CONCURRENTLY */
+#define ShareLock 5 /* CREATE INDEX (WITHOUT CONCURRENTLY) */
+#define ShareRowExclusiveLock 6 /* like EXCLUSIVE MODE, but allows ROW
+ * SHARE */
+#define ExclusiveLock 7 /* blocks ROW SHARE/SELECT...FOR UPDATE */
+#define AccessExclusiveLock 8 /* ALTER TABLE, DROP TABLE, VACUUM FULL,
+ * and unqualified LOCK TABLE */
+
+#define MaxLockMode 8
+
+
+/* WAL representation of an AccessExclusiveLock on a table */
+typedef struct xl_standby_lock
+{
+ TransactionId xid; /* xid of holder of AccessExclusiveLock */
+ Oid dbOid; /* DB containing table */
+ Oid relOid; /* OID of table */
+} xl_standby_lock;
+
+#endif /* LOCKDEFS_H_ */