nsr-recon: fix entry-count error when logs are preallocated

Change-Id: I48dc83f5ea5a47ec8ef7eaadf8ecbc5f2a725fd3
Signed-off-by: Jeff Darcy <jdarcy@redhat.com>

1 files changed, 65 insertions, 12 deletions

diff --git a/xlators/cluster/nsr-recon/src/recon_xlator.c b/xlators/cluster/nsr-recon/src/recon_xlator.c
index b527633d8..da14aab93 100644
--- a/xlators/cluster/nsr-recon/src/recon_xlator.c
+++ b/xlators/cluster/nsr-recon/src/recon_xlator.c
@@ -114,26 +114,79 @@ static void get_frame(nsr_recon_private_t *priv,
         GF_ASSERT(0);
 }
 
+#define ENTRY_SIZE 128
+
+long
+get_entry_count (char *path)
+{
+        int             fd;
+        struct stat     buf;
+        unsigned long   entries         = -1;
+        long            min;            /* last entry not known to be empty */
+        long            max;            /* first entry known to be empty */
+        long            curr;
+        char            entry[ENTRY_SIZE];
+        void            *err_label      = &&done;
+
+        fd = open(path,O_RDONLY);
+        if (fd < 0) {
+                goto *err_label;
+        }
+        err_label = &&close_fd;
+
+        if (fstat(fd,&buf) < 0) {
+                goto *err_label;
+        }
+
+        min = 0;
+        max = buf.st_size / ENTRY_SIZE;
+        printf("max = %ld\n",max);
+
+        while ((min+1) < max) {
+                curr = (min + max) / 2;
+                printf("trying entry %ld\n",curr);
+                if (lseek(fd,curr*ENTRY_SIZE,SEEK_SET) < 0) {
+                        goto *err_label;
+                }
+                if (read(fd,entry,sizeof(entry)) != sizeof(entry)) {
+                        goto *err_label;
+                }
+                if ((entry[0] == '_') && (entry[1] == 'P')) {
+                        min = curr;
+                }
+                else {
+                        max = curr;
+                }
+        }
+
+        entries = max;
+
+close_fd:
+        close(fd);
+done:
+        return entries;
+}
+
 // Get the term info for the term number specified
 void nsr_recon_libchangelog_get_this_term_info(xlator_t *this, char *bp, int32_t term, nsr_recon_last_term_info_t *lt)
 {
-        struct stat buf;
         char path[PATH_MAX];
+        long entries;
 
         bzero(lt, sizeof(nsr_recon_last_term_info_t));
         lt->last_term = term;
         sprintf(path,"%s/%s%d",bp,"TERM.",term);
-        if (!stat(path, &buf) && (buf.st_size > 128)) {
-                if (buf.st_size <= 128) {
-                        lt->first_index = 0;
-                        lt->last_index = 0;
-                        lt->commited_ops = 0;
-                }
-                else {
-                        lt->first_index = 1;
-                        lt->last_index = ((buf.st_size  - 128)/128) + 1 ;
-                        lt->commited_ops = lt->last_index - lt->first_index + 1;
-                }
+        entries = get_entry_count(path);
+        if (entries > 1) {
+                /* The first entry is actually a header. */
+                lt->first_index = 1;
+                /*
+                 * This seems wrong, because it means that last_index*128 will
+                 * be exactly at EOF and commited_ops will be one greater than
+                 * it should be.  Maybe some other code makes the exact
+                 * opposite mistake to compensate.
+                 */
+                lt->last_index = lt->commited_ops = (int)entries;
         }
         recon_main_log (this->name, GF_LOG_INFO, "for term=%d got first_index=%d last_index=%d commited_ops=%d\n",
                         term, lt->first_index, lt->last_index, lt->commited_ops);