Add CHECK_FOR_INTERRUPTS in contrib/pg_buffercache functions.

This commit adds CHECK_FOR_INTERRUPTS to loops iterating over shared
buffers in several pg_buffercache functions, allowing them to be
interrupted during long-running operations.

Backpatch to all supported versions. Add CHECK_FOR_INTERRUPTS to the
loop in pg_buffercache_pages() in all supported branches, and to
pg_buffercache_summary() and pg_buffercache_usage_counts() in version
16 and newer.

Author: SATYANARAYANA NARLAPURAM <satyanarlapuram@gmail.com>
Discussion: https://postgr.es/m/CAHg+QDcejeLx7WunFT3DX6XKh1KshvGKa8F5au8xVhqVvvQPRw@mail.gmail.com
Backpatch-through: 13

diff --git a/contrib/pg_buffercache/pg_buffercache_pages.c b/contrib/pg_buffercache/pg_buffercache_pages.c
index ae0291e6e96df2fc0a4530507022cce6c71875d5..3df04c98959e1257bf3652243f1b21cb350693e8 100644 (file)
--- a/contrib/pg_buffercache/pg_buffercache_pages.c
+++ b/contrib/pg_buffercache/pg_buffercache_pages.c
@@ -194,6 +194,8 @@ pg_buffercache_pages(PG_FUNCTION_ARGS)
                        BufferDesc *bufHdr;
                        uint32          buf_state;
 
+                       CHECK_FOR_INTERRUPTS();
+
                        bufHdr = GetBufferDescriptor(i);
                        /* Lock each buffer header before inspecting. */
                        buf_state = LockBufHdr(bufHdr);
@@ -560,6 +562,8 @@ pg_buffercache_summary(PG_FUNCTION_ARGS)
                BufferDesc *bufHdr;
                uint32          buf_state;
 
+               CHECK_FOR_INTERRUPTS();
+
                /*
                 * This function summarizes the state of all headers. Locking the
                 * buffer headers wouldn't provide an improved result as the state of
@@ -620,6 +624,8 @@ pg_buffercache_usage_counts(PG_FUNCTION_ARGS)
                uint32          buf_state = pg_atomic_read_u32(&bufHdr->state);
                int                     usage_count;
 
+               CHECK_FOR_INTERRUPTS();
+
                usage_count = BUF_STATE_GET_USAGECOUNT(buf_state);
                usage_counts[usage_count]++;