d91a1f3398f1978990bc18340a53d458f59fc0eb
braney
  Tue Jan 14 10:09:00 2020 -0800
allow user to set trackDbCacheDir to null to disable

diff --git src/hg/lib/trackDbCache.c src/hg/lib/trackDbCache.c
index a0069f6..d2e9a0b 100644
--- src/hg/lib/trackDbCache.c
+++ src/hg/lib/trackDbCache.c
@@ -378,26 +378,26 @@
 char newName[(SHA_DIGEST_LENGTH + 1) * 2];
 hexBinaryString(hash,  SHA_DIGEST_LENGTH, newName, (SHA_DIGEST_LENGTH + 1) * 2);
 
 cloneTdbListToSharedMem(newName, list, size, trackDbUrl);
 }
 
 boolean trackDbCacheOn()
 /* Check to see if we're caching trackDb contents. */
 {
 static boolean checkedCache = FALSE;
 static boolean doCache = FALSE;
 
 if (!checkedCache)
     {
     trackDbCacheDir = cfgOption("cacheTrackDbDir");
-    if (trackDbCacheDir != NULL)
+    if (isNotEmpty(trackDbCacheDir))
         {
         makeDirsOnPath(trackDbCacheDir);
         doCache = TRUE;
         }
 
     checkedCache = TRUE;
     }
 
 return doCache;
 }