[t:3988] #3988 Improve thrashing stats. Still need to make available to engine status.

git-svn-id: file:///svn/toku/tokudb@35880 c7de825b-a66e-492c-adef-691d508d4ae1

newbrt/brt-internal.h

@@ -773,6 +773,8 @@ typedef struct brt_status {
     u_int64_t dsn_gap;                     // dsn has detected a gap in continuity of root-to-leaf path (internal node was evicted and re-read)
     u_int64_t bytes_leaf;                  // memory used by leaf nodes
     u_int64_t bytes_nonleaf;               // memory used by nonleaf nodes
+    uint64_t  total_searches;              // total number of searches
+    uint64_t  total_retries;               // total number of search retries due to TRY_AGAIN
     uint64_t  max_search_excess_retries;   // max number of excess search retries (retries - treeheight) due to TRY_AGAIN
     uint64_t  max_search_root_tries;       // max number of times root node was fetched in a single search
     uint64_t  search_root_retries;         // number of searches that required the root node to be fetched more than once

newbrt/brt.c

@@ -6260,17 +6260,13 @@ toku_brt_search (BRT brt, brt_search_t *search, BRT_GET_CALLBACK_FUNCTION getf,
 // All searches are performed through this function.
 {
     int r;
-    uint retrycount = 0;   // How many retries did it take to get the result?
+    uint trycount = 0;     // How many tries did it take to get the result?
     uint root_tries = 0;   // How many times did we fetch the root node from disk?
     uint tree_height;      // How high is the tree?  This is the height of the root node plus one (leaf is at height 0).
-    BOOL retry = false;    // Have we attempted this search yet?  
 
 try_again:
     
-    if (retry)             // don't count first attempt as a retry
-	retrycount++;
-    retry = true;
-
+    trycount++;
     assert(brt->h);
 
     u_int32_t fullhash;
@@ -6372,6 +6368,9 @@ try_again:
     }
 
     {   // accounting (to detect and measure thrashing)
+	uint retrycount = trycount - 1;         // how many retries were needed?
+	brt_status.total_searches++;
+	brt_status.total_retries += retrycount;
 	if (root_tries > 1) {                   // if root was read from disk more than once
 	    brt_status.search_root_retries++;   
 	    if (root_tries > brt_status.max_search_root_tries)