close[t:5109] address some comments from code review concerning the naming of...

close[t:5109] address some comments from code review concerning the naming of functions that remove an ft from memory vs removing a ft from the filesystem.


git-svn-id: file:///svn/toku/tokudb@44741 c7de825b-a66e-492c-adef-691d508d4ae1

ft/ft-ops.c

@@ -3283,7 +3283,7 @@ ft_handle_open(FT_HANDLE ft_h, const char *fname_in_env, int is_create, int only
             if (!needed) {
                 //Close immediately.
                 char *error_string = NULL;
-                r = toku_remove_ft(ft, &error_string, false, ZERO_LSN);
+                r = toku_ft_evict_from_memory(ft, &error_string, false, ZERO_LSN);
                 lazy_assert_zero(r);
             }
         }
@@ -5488,7 +5488,7 @@ int toku_ft_handle_set_panic(FT_HANDLE brt, int panic, char *panic_string) {
 //           synchronize with begin checkpoint.
 // Contract: the iname of the ft should never be reused.
 int 
-toku_ft_remove_on_commit(FT_HANDLE handle, TOKUTXN txn) {
+toku_ft_unlink_on_commit(FT_HANDLE handle, TOKUTXN txn) {
     int r;
     CACHEFILE cf;
 
@@ -5516,7 +5516,7 @@ toku_ft_remove_on_commit(FT_HANDLE handle, TOKUTXN txn) {
 //         close works in toku_cachefile_close();
 // Requires: serialized with begin checkpoint
 void 
-toku_ft_remove(FT_HANDLE handle) {
+toku_ft_unlink(FT_HANDLE handle) {
     CACHEFILE cf;
     cf = handle->ft->cf;
     toku_cachefile_unlink_on_close(cf);

ft/ft.c

@@ -544,34 +544,40 @@ toku_ft_note_ft_handle_open(FT ft, FT_HANDLE live) {
     toku_ft_release_reflock(ft);
 }
 
-bool
-toku_ft_needed_unlocked(FT h) 
-// Effect: Return true iff the reference count is positive.
-{
-    return !toku_list_empty(&h->live_ft_handles) || toku_omt_size(h->txns) != 0 || h->pinned_by_checkpoint;
-}
-
-BOOL
-toku_ft_has_one_reference_unlocked(FT ft) {
+// the reference count for a ft is the number of txn's that
+// touched it plus the number of open handles plus one if
+// pinned by a checkpoint.
+static int
+ft_get_reference_count(FT ft) {
     u_int32_t pinned_by_checkpoint = ft->pinned_by_checkpoint ? 1 : 0;
     u_int32_t num_txns = toku_omt_size(ft->txns);
     int num_handles = toku_list_num_elements_est(&ft->live_ft_handles);
-    return ((pinned_by_checkpoint + num_txns + num_handles) == 1);
+    return pinned_by_checkpoint + num_txns + num_handles;
+}
+
+// a ft is needed in memory iff its reference count is non-zero
+bool
+toku_ft_needed_unlocked(FT ft) {
+    return ft_get_reference_count(ft) != 0;
 }
 
+// get the reference count and return true if it was 1
+bool
+toku_ft_has_one_reference_unlocked(FT ft) {
+    return ft_get_reference_count(ft) == 1;
+}
 
-// Close brt.  If opsln_valid, use given oplsn as lsn in brt header instead of logging 
-// the close and using the lsn provided by logging the close.  (Subject to constraint 
-// that if a newer lsn is already in the dictionary, don't overwrite the dictionary.)
-int toku_remove_ft (FT h, char **error_string, BOOL oplsn_valid, LSN oplsn)
-// Requires: we hold the open_close lock (because we are closing) and the multi_operation lock (to prevent checkpoints).
-{
+// evict a ft from memory by closing its cachefile. any future work
+// will have to read in the ft in a new cachefile and new FT object.
+int toku_ft_evict_from_memory(FT ft, char **error_string, BOOL oplsn_valid, LSN oplsn) {
     int r = 0;
-    // Must do this work before closing the cf
-    if (h->cf) {
-        if (error_string) assert(*error_string == 0);
-        r = toku_cachefile_close(&h->cf, error_string, oplsn_valid, oplsn);
-        if (r==0 && error_string) assert(*error_string == 0);
+    assert(ft->cf);
+    if (error_string) {
+        assert(*error_string == 0);
+    }
+    r = toku_cachefile_close(&ft->cf, error_string, oplsn_valid, oplsn);
+    if (r == 0 && error_string) {
+        assert(*error_string == 0);
     }
     return r;
 }
@@ -989,13 +995,13 @@ toku_ft_remove_reference(FT ft, bool oplsn_valid, LSN oplsn, remove_ft_ref_callb
         toku_ft_grab_reflock(ft);
 
         remove_ref(ft, extra);
-        BOOL needed = toku_ft_needed_unlocked(ft);
+        bool needed = toku_ft_needed_unlocked(ft);
         toku_ft_release_reflock(ft);
         if (!needed) {
             // close header
             char *error_string = NULL;
             int r;
-            r = toku_remove_ft(ft, &error_string, oplsn_valid, oplsn);
+            r = toku_ft_evict_from_memory(ft, &error_string, oplsn_valid, oplsn);
             assert_zero(r);
             assert(error_string == NULL);
         }

ft/ft.h

@@ -15,13 +15,11 @@
 #include "ft-ops.h"
 #include "compress.h"
 
-// remove a ft, transactionless.
-// if the ft is being checkpointed, it will be removed after checkpoint.
-void toku_ft_remove(FT_HANDLE handle);
+// unlink a ft from the filesystem, without a txn.
+void toku_ft_unlink(FT_HANDLE handle);
 
-// remove a ft using the given txn. when the txn commits, the ft is removed.
-// if the ft is being checkpointed, it will be removed after checkpoint.
-int toku_ft_remove_on_commit(FT_HANDLE handle, TOKUTXN txn) __attribute__((__warn_unused_result__));
+// unlink a ft from the filesystem when the given txn commits.
+int toku_ft_unlink_on_commit(FT_HANDLE handle, TOKUTXN txn) __attribute__((__warn_unused_result__));
 
 //Effect: suppresses rollback logs
 void toku_ft_suppress_rollbacks(FT h, TOKUTXN txn);
@@ -42,9 +40,12 @@ void toku_ft_free (FT h);
 int toku_read_ft_and_store_in_cachefile (FT_HANDLE brt, CACHEFILE cf, LSN max_acceptable_lsn, FT *header, BOOL* was_open);
 void toku_ft_note_ft_handle_open(FT ft, FT_HANDLE live);
 
-int toku_ft_needed_unlocked(FT h);
-BOOL toku_ft_has_one_reference_unlocked(FT ft);
-int toku_remove_ft (FT h, char **error_string, BOOL oplsn_valid, LSN oplsn)  __attribute__ ((warn_unused_result));
+bool toku_ft_needed_unlocked(FT ft);
+bool toku_ft_has_one_reference_unlocked(FT ft);
+
+// evict a ft from memory by closing its cachefile. any future work
+// will have to read in the ft in a new cachefile and new FT object.
+int toku_ft_evict_from_memory(FT ft, char **error_string, BOOL oplsn_valid, LSN oplsn)  __attribute__ ((warn_unused_result));
 
 FT_HANDLE toku_ft_get_only_existing_ft_handle(FT h);
 

ft/recover.c

@@ -876,7 +876,7 @@ static int toku_recover_fdelete (struct logtype_fdelete *l, RECOVER_ENV renv) {
     struct file_map_tuple *tuple;
     r = file_map_find(&renv->fmap, l->filenum, &tuple);
     if (r == 0) {
-        r = toku_ft_remove_on_commit(tuple->ft_handle, txn);
+        r = toku_ft_unlink_on_commit(tuple->ft_handle, txn);
     }
     return 0;
 }

src/ydb.c

@@ -2473,14 +2473,14 @@ toku_env_dbremove(DB_ENV * env, DB_TXN *txn, const char *fname, const char *dbna
             if (toku_db_pre_acquire_table_lock(db, txn) != 0) {
                 r = DB_LOCK_NOTGRANTED;
             } else {
-                // The ft will be removed when the txn commits
-                r = toku_ft_remove_on_commit(db->i->ft_handle, db_txn_struct_i(txn)->tokutxn);
+                // The ft will be unlinked when the txn commits
+                r = toku_ft_unlink_on_commit(db->i->ft_handle, db_txn_struct_i(txn)->tokutxn);
                 assert_zero(r);
             }
         }
         else {
-            // Remove the ft without a txn
-            toku_ft_remove(db->i->ft_handle);
+            // unlink the ft without a txn
+            toku_ft_unlink(db->i->ft_handle);
         }
     }