Eliminate some repetitive coding in tuplesort.c.

Use a macro LogicalTapeReadExact() to encapsulate the error check when
we want to read an exact number of bytes from a "tape".  Per a suggestion
of Takahiro Itagaki.

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 00137032505159a50b8388b871effa243ff3a874..dae73f15afaa2af1716e516503b5dff5ee06a7ae 100644 (file)
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -120,9 +120,9 @@
 
 
 /* sort-type codes for sort__start probes */
-#define HEAP_SORT  0
-#define INDEX_SORT 1
-#define DATUM_SORT 2
+#define HEAP_SORT      0
+#define INDEX_SORT     1
+#define DATUM_SORT     2
 #define CLUSTER_SORT   3
 
 /* GUC variables */
@@ -435,6 +435,13 @@ struct Tuplesortstate
  * a lot better than what we were doing before 7.3.
  */
 
+/* When using this macro, beware of double evaluation of len */
+#define LogicalTapeReadExact(tapeset, tapenum, ptr, len) \
+   do { \
+       if (LogicalTapeRead(tapeset, tapenum, ptr, len) != (size_t) (len)) \
+           elog(ERROR, "unexpected end of data"); \
+   } while(0)
+
 
 static Tuplesortstate *tuplesort_begin_common(int workMem, bool randomAccess);
 static void puttuple_common(Tuplesortstate *state, SortTuple *tuple);
@@ -2576,8 +2583,8 @@ getlen(Tuplesortstate *state, int tapenum, bool eofOK)
 {
    unsigned int len;
 
-   if (LogicalTapeRead(state->tapeset, tapenum, (void *) &len,
-                       sizeof(len)) != sizeof(len))
+   if (LogicalTapeRead(state->tapeset, tapenum,
+                       &len, sizeof(len)) != sizeof(len))
        elog(ERROR, "unexpected end of tape");
    if (len == 0 && !eofOK)
        elog(ERROR, "unexpected end of data");
@@ -2810,14 +2817,11 @@ readtup_heap(Tuplesortstate *state, SortTuple *stup,
    USEMEM(state, GetMemoryChunkSpace(tuple));
    /* read in the tuple proper */
    tuple->t_len = tuplen;
-   if (LogicalTapeRead(state->tapeset, tapenum,
-                       (void *) tupbody,
-                       tupbodylen) != (size_t) tupbodylen)
-       elog(ERROR, "unexpected end of data");
+   LogicalTapeReadExact(state->tapeset, tapenum,
+                        tupbody, tupbodylen);
    if (state->randomAccess)    /* need trailing length word? */
-       if (LogicalTapeRead(state->tapeset, tapenum, (void *) &tuplen,
-                           sizeof(tuplen)) != sizeof(tuplen))
-           elog(ERROR, "unexpected end of data");
+       LogicalTapeReadExact(state->tapeset, tapenum,
+                            &tuplen, sizeof(tuplen));
    stup->tuple = (void *) tuple;
    /* set up first-column key value */
    htup.t_len = tuple->t_len + MINIMAL_TUPLE_OFFSET;
@@ -2998,20 +3002,16 @@ readtup_cluster(Tuplesortstate *state, SortTuple *stup,
    /* Reconstruct the HeapTupleData header */
    tuple->t_data = (HeapTupleHeader) ((char *) tuple + HEAPTUPLESIZE);
    tuple->t_len = t_len;
-   if (LogicalTapeRead(state->tapeset, tapenum,
-                       &tuple->t_self,
-                       sizeof(ItemPointerData)) != sizeof(ItemPointerData))
-       elog(ERROR, "unexpected end of data");
+   LogicalTapeReadExact(state->tapeset, tapenum,
+                        &tuple->t_self, sizeof(ItemPointerData));
    /* We don't currently bother to reconstruct t_tableOid */
    tuple->t_tableOid = InvalidOid;
    /* Read in the tuple body */
-   if (LogicalTapeRead(state->tapeset, tapenum,
-                       tuple->t_data, tuple->t_len) != tuple->t_len)
-       elog(ERROR, "unexpected end of data");
+   LogicalTapeReadExact(state->tapeset, tapenum,
+                        tuple->t_data, tuple->t_len);
    if (state->randomAccess)    /* need trailing length word? */
-       if (LogicalTapeRead(state->tapeset, tapenum, &tuplen,
-                           sizeof(tuplen)) != sizeof(tuplen))
-           elog(ERROR, "unexpected end of data");
+       LogicalTapeReadExact(state->tapeset, tapenum,
+                            &tuplen, sizeof(tuplen));
    stup->tuple = (void *) tuple;
    /* set up first-column key value, if it's a simple column */
    if (state->indexInfo->ii_KeyAttrNumbers[0] != 0)
@@ -3243,13 +3243,11 @@ readtup_index(Tuplesortstate *state, SortTuple *stup,
    IndexTuple  tuple = (IndexTuple) palloc(tuplen);
 
    USEMEM(state, GetMemoryChunkSpace(tuple));
-   if (LogicalTapeRead(state->tapeset, tapenum, (void *) tuple,
-                       tuplen) != tuplen)
-       elog(ERROR, "unexpected end of data");
+   LogicalTapeReadExact(state->tapeset, tapenum,
+                        tuple, tuplen);
    if (state->randomAccess)    /* need trailing length word? */
-       if (LogicalTapeRead(state->tapeset, tapenum, (void *) &tuplen,
-                           sizeof(tuplen)) != sizeof(tuplen))
-           elog(ERROR, "unexpected end of data");
+       LogicalTapeReadExact(state->tapeset, tapenum,
+                            &tuplen, sizeof(tuplen));
    stup->tuple = (void *) tuple;
    /* set up first-column key value */
    stup->datum1 = index_getattr(tuple,
@@ -3357,9 +3355,8 @@ readtup_datum(Tuplesortstate *state, SortTuple *stup,
    else if (state->datumTypeByVal)
    {
        Assert(tuplen == sizeof(Datum));
-       if (LogicalTapeRead(state->tapeset, tapenum, (void *) &stup->datum1,
-                           tuplen) != tuplen)
-           elog(ERROR, "unexpected end of data");
+       LogicalTapeReadExact(state->tapeset, tapenum,
+                            &stup->datum1, tuplen);
        stup->isnull1 = false;
        stup->tuple = NULL;
    }
@@ -3367,9 +3364,8 @@ readtup_datum(Tuplesortstate *state, SortTuple *stup,
    {
        void       *raddr = palloc(tuplen);
 
-       if (LogicalTapeRead(state->tapeset, tapenum, raddr,
-                           tuplen) != tuplen)
-           elog(ERROR, "unexpected end of data");
+       LogicalTapeReadExact(state->tapeset, tapenum,
+                            raddr, tuplen);
        stup->datum1 = PointerGetDatum(raddr);
        stup->isnull1 = false;
        stup->tuple = raddr;
@@ -3377,9 +3373,8 @@ readtup_datum(Tuplesortstate *state, SortTuple *stup,
    }
 
    if (state->randomAccess)    /* need trailing length word? */
-       if (LogicalTapeRead(state->tapeset, tapenum, (void *) &tuplen,
-                           sizeof(tuplen)) != sizeof(tuplen))
-           elog(ERROR, "unexpected end of data");
+       LogicalTapeReadExact(state->tapeset, tapenum,
+                            &tuplen, sizeof(tuplen));
 }
 
 static void