vim-patch:8.0.0190

Problem:    Detecting duplicate tags uses a slow linear search.
Solution:   Use a much faster hash table solution. (James McCoy, closes vim/vim#1046)
            But don't add hi_keylen, it makes hash tables 50% bigger.

810f9c361c

src/nvim/tag.c

@@ -73,9 +73,9 @@ typedef struct {
 } pat_T;
 
 /*
- * The matching tags are first stored in ga_match[].  In which one depends on
+ * The matching tags are first stored in one of the ht_match[] hash tables.  In
- * the priority of the match.
+ * which one depends on the priority of the match.
- * At the end, the matches from ga_match[] are concatenated, to make a list
+ * At the end, the matches from ht_match[] are concatenated, to make a list
  * sorted on priority.
  */
 #define MT_ST_CUR       0               /* static match in current file */
@@ -1122,11 +1122,9 @@ find_tags (
   int save_emsg_off;
 
 
-  struct match_found {
+  char_u *mfp;
-    int len;                    /* nr of chars of match[] to be compared */
+  hashtab_T ht_match[MT_COUNT];
-    char_u match[1];            /* actually longer */
+  hash_T hash = 0;
-  } *mfp, *mfp2;
-  garray_T ga_match[MT_COUNT];
   int match_count = 0;                          /* number of matches found */
   char_u      **matches;
   int mtt;
@@ -1186,7 +1184,7 @@ find_tags (
   lbuf = xmalloc(lbuf_size);
   tag_fname = xmalloc(MAXPATHL + 1);
   for (mtt = 0; mtt < MT_COUNT; ++mtt)
-    ga_init(&ga_match[mtt], (int)sizeof(struct match_found *), 100);
+    hash_init(&ht_match[mtt]);
 
   STRCPY(tag_fname, "from cscope");             /* for error messages */
 
@@ -1752,9 +1750,11 @@ parse_line:
         }
 
         /*
-         * If a match is found, add it to ga_match[].
+         * If a match is found, add it to ht_match[].
          */
         if (match) {
+          int len = 0;
+
           if (use_cscope) {
             /* Don't change the ordering, always use the same table. */
             mtt = MT_GL_OTH;
@@ -1790,36 +1790,28 @@ parse_line:
           }
 
           /*
-           * Add the found match in ga_match[mtt], avoiding duplicates.
+           * Add the found match in ht_match[mtt].
            * Store the info we need later, which depends on the kind of
            * tags we are dealing with.
            */
-          ga_grow(&ga_match[mtt], 1);
-          {
-            int len;
-
           if (help_only) {
 # define ML_EXTRA 3
-              /*
+            // Append the help-heuristic number after the tagname, for
-               * Append the help-heuristic number after the
+            // sorting it later.  The heuristic is ignored for
-               * tagname, for sorting it later.
+            // detecting duplicates.
-               */
+            // The format is {tagname}@{lang}NUL{heuristic}NUL
             *tagp.tagname_end = NUL;
             len = (int)(tagp.tagname_end - tagp.tagname);
-              mfp = xmalloc(sizeof(struct match_found) + len + 10 + ML_EXTRA);
+            mfp = xmalloc(sizeof(char_u) + len + 10 + ML_EXTRA + 1);
-              /* "len" includes the language and the NUL, but
+
-               * not the priority. */
+            p = mfp;
-              mfp->len = len + ML_EXTRA + 1;
-#define ML_HELP_LEN 6
-              p = mfp->match;
             STRCPY(p, tagp.tagname);
             p[len] = '@';
             STRCPY(p + len + 1, help_lang);
             sprintf((char *)p + len + 1 + ML_EXTRA, "%06d",
                     help_heuristic(tagp.tagname,
                                    match_re ? matchoff : 0, !match_no_ic)
-                  + help_pri
+                    + help_pri);
-                  );
 
             *tagp.tagname_end = TAB;
           } else if (name_only)   {
@@ -1834,35 +1826,33 @@ parse_line:
 
               if (tagp.command + 2 < temp_end) {
                 len = (int)(temp_end - tagp.command - 2);
-                  mfp = xmalloc(sizeof(struct match_found) + len);
+                mfp = xmalloc(sizeof(char_u) + len + 1);
-                  mfp->len = len + 1;                 /* include the NUL */
+                STRLCPY(mfp, tagp.command + 2, len + 1);
-                  p = mfp->match;
-                  STRLCPY(p, tagp.command + 2, len + 1);
               } else
                 mfp = NULL;
               get_it_again = FALSE;
             } else {
               len = (int)(tagp.tagname_end - tagp.tagname);
-                mfp = xmalloc(sizeof(struct match_found) + len);
+              mfp = xmalloc(sizeof(char_u) + len + 1);
-                mfp->len = len + 1;               /* include the NUL */
+              STRLCPY(mfp, tagp.tagname, len + 1);
-                p = mfp->match;
-                STRLCPY(p, tagp.tagname, len + 1);
 
               /* if wanted, re-read line to get long form too */
               if (State & INSERT)
                 get_it_again = p_sft;
             }
           } else {
+#define TAG_SEP 0x01
+            size_t tag_fname_len = STRLEN(tag_fname);
             /* Save the tag in a buffer.
+             * Use 0x01 to separate fields (Can't use NUL, because the
+             * hash key is terminated by NUL).
              * Emacs tag: <mtt><tag_fname><NUL><ebuf><NUL><lbuf>
              * other tag: <mtt><tag_fname><NUL><NUL><lbuf>
              * without Emacs tags: <mtt><tag_fname><NUL><lbuf>
              */
-              len = (int)STRLEN(tag_fname)
+            len = (int)tag_fname_len + (int)STRLEN(lbuf) + 3;
-                    + (int)STRLEN(lbuf) + 3;
+            mfp = xmalloc(sizeof(char_u) + len + 1);
-              mfp = xmalloc(sizeof(struct match_found) + len);
+            p = mfp;
-              mfp->len = len;
-              p = mfp->match;
             p[0] = mtt;
             STRCPY(p + 1, tag_fname);
 #ifdef BACKSLASH_IN_FILENAME
@@ -1870,38 +1860,34 @@ parse_line:
              * both path/file and path\file. */
             slash_adjust(p + 1);
 #endif
-              s = p + 1 + STRLEN(tag_fname) + 1;
+            p[tag_fname_len + 1] = TAG_SEP;
+            s = p + 1 + tag_fname_len + 1;
             STRCPY(s, lbuf);
           }
 
           if (mfp != NULL) {
-              /*
+            hashitem_T *hi;
-               * Don't add identical matches.
+
-               * This can take a lot of time when finding many
+            // Don't add identical matches.
-               * matches, check for CTRL-C now and then.
+            // Add all cscope tags, because they are all listed.
-               * Add all cscope tags, because they are all listed.
+            // "mfp" is used as a hash key, there is a NUL byte to end
-               */
+            // the part matters for comparing, more bytes may follow
+            // after it.  E.g. help tags store the priority after the
+            // NUL.
             if (use_cscope)
-                i = -1;
+              hash++;
             else
-                for (i = ga_match[mtt].ga_len; --i >= 0 && !got_int; ) {
+              hash = hash_hash(mfp);
-                  mfp2 = ((struct match_found **)
+            hi = hash_lookup(&ht_match[mtt], (const char *)mfp,
-                          (ga_match[mtt].ga_data))[i];
+                             STRLEN(mfp), hash);
-                  if (mfp2->len == mfp->len
+            if (HASHITEM_EMPTY(hi)) {
-                      && memcmp(mfp2->match, mfp->match,
+              hash_add_item(&ht_match[mtt], hi, mfp, hash);
-                          (size_t)mfp->len) == 0)
-                    break;
-                  fast_breakcheck();
-                }
-              if (i < 0) {
-                ((struct match_found **)(ga_match[mtt].ga_data))
-                [ga_match[mtt].ga_len++] = mfp;
               ++match_count;
             } else
+              // duplicate tag, drop it
               xfree(mfp);
           }
         }
-        }
         if (use_cscope && eof)
           break;
       }   /* forever */
@@ -1962,7 +1948,7 @@ findtag_end:
   xfree(tag_fname);
 
   /*
-   * Move the matches from the ga_match[] arrays into one list of
+   * Move the matches from the ht_match[] arrays into one list of
    * matches.  When retval == FAIL, free the matches.
    */
   if (retval == FAIL)
@@ -1974,20 +1960,27 @@ findtag_end:
     matches = NULL;
   match_count = 0;
   for (mtt = 0; mtt < MT_COUNT; ++mtt) {
-    for (int i = 0; i < ga_match[mtt].ga_len; ++i) {
+    hashitem_T *hi;
-      mfp = ((struct match_found **)(ga_match[mtt].ga_data))[i];
+    long todo = (long)ht_match[mtt].ht_used;
-      if (matches == NULL)
+
+    for (hi = ht_match[mtt].ht_array; todo > 0; hi++) {
+      if (!HASHITEM_EMPTY(hi)) {
+        mfp = hi->hi_key;
+        if (matches == NULL) {
           xfree(mfp);
-      else {
+        } else {
-        /* To avoid allocating memory again we turn the struct
+          // now change the TAG_SEP back to NUL
-         * match_found into a string.  For help the priority was not
+          for (p = mfp; *p != NUL; p++) {
-         * included in the length. */
+            if (*p == TAG_SEP) {
-        memmove(mfp, mfp->match,
+              *p = NUL;
-            (size_t)(mfp->len + (help_only ? ML_HELP_LEN : 0)));
+            }
+          }
           matches[match_count++] = (char_u *)mfp;
         }
+        todo--;
       }
-    ga_clear(&ga_match[mtt]);
+    }
+    hash_clear(&ht_match[mtt]);
   }
 
   *matchesp = matches;