Changeset 26568

Timestamp:

12/12/08 14:34:36 (4 years ago)

Author:

kazuho

Message:

impl. top n sort, still need to make topn_set an aggregate function

Files:

• platform/mysql/top-n-sort/top-n-sort.c (modified) (3 diffs)

platform/mysql/top-n-sort/top-n-sort.c

@@ -32 +32 @@
 
 typedef struct _topn_info {
-  size_t refcnt;
-  size_t count;
+  int refcnt;
+  int count;
   topn_item items[MAX_ITEMS];
 } topn_info;
@@ -113 +113 @@
 long long topn_set(UDF_INIT *initid, UDF_ARGS *args, char *is_null, char *error)
 {
-  // TODO
+  int max_items = (int)*(long long*)args->args[0];
+  long long id = *(long long*)args->args[1],
+    value = *(long long*)args->args[2];
+  topn_info *info = initid->ptr;
+  int keep;
+  
+  for (keep = info->count - 1; keep >= 0; keep--) {
+    if (info->items[keep].value < value
+        || (info->items[keep].value == value && info->items[keep].id < id)) {
+      break;
+    }
+  }
+  if (i == max_items - 1) {
+    return 0; // cannot add
+  }
+  if (info->count < max_items) {
+    info->count++;
+  }
+  for (i = cnt - 2; i > keep; i--) {
+    memcpy(info->items + i + 1, info->items + i, sizeof(info->items[0]));
+  }
+  info->items[keep + 1].id = id;
+  info->items[keep + 1].value = value;
   return 0;
 }
@@ -141 +163 @@
 {
   topn_info *info = initid->ptr;
-  size_t idx = (size_t)*(long long*)args->args[0];
+  int idx = (int)*(long long*)args->args[0];
   
-  return idx < info->count ? info->items[idx].id : 0;
+  return 0 <= idx && idx < info->count ? info->items[idx].id : 0;
 }