1 files changed, 51 insertions, 0 deletions
diff --git a/src/include/storage/proclist_types.h b/src/include/storage/proclist_types.h
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+++ b/src/include/storage/proclist_types.h
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+/*-------------------------------------------------------------------------
+ *
+ * proclist_types.h
+ *		doubly-linked lists of pgprocnos
+ *
+ * See proclist.h for functions that operate on these types.
+ *
+ * Portions Copyright (c) 2016-2020, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		src/include/storage/proclist_types.h
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef PROCLIST_TYPES_H
+#define PROCLIST_TYPES_H
+
+/*
+ * A node in a doubly-linked list of processes.  The link fields contain
+ * the 0-based PGPROC indexes of the next and previous process, or
+ * INVALID_PGPROCNO in the next-link of the last node and the prev-link
+ * of the first node.  A node that is currently not in any list
+ * should have next == prev == 0; this is not a possible state for a node
+ * that is in a list, because we disallow circularity.
+ */
+typedef struct proclist_node
+{
+	int			next;			/* pgprocno of the next PGPROC */
+	int			prev;			/* pgprocno of the prev PGPROC */
+} proclist_node;
+
+/*
+ * Header of a doubly-linked list of PGPROCs, identified by pgprocno.
+ * An empty list is represented by head == tail == INVALID_PGPROCNO.
+ */
+typedef struct proclist_head
+{
+	int			head;			/* pgprocno of the head PGPROC */
+	int			tail;			/* pgprocno of the tail PGPROC */
+} proclist_head;
+
+/*
+ * List iterator allowing some modifications while iterating.
+ */
+typedef struct proclist_mutable_iter
+{
+	int			cur;			/* pgprocno of the current PGPROC */
+	int			next;			/* pgprocno of the next PGPROC */
+} proclist_mutable_iter;
+
+#endif							/* PROCLIST_TYPES_H */