vim-patch:8.0.1284: loading file type detection slows down startup

Problem:    Loading file type detection slows down startup.
Solution:   Store the last pattern of an autocommand event to make appending
            quicker.
https://github.com/vim/vim/commit/462455ee8b81cb5709007d91248ac4a88308d6e9

1 files changed, 79 insertions, 54 deletions

diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 52686f6651..02f72dbce3 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -1,9 +1,7 @@
 // This is an open source non-commercial project. Dear PVS-Studio, please check
 // it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
-/*
- * fileio.c: read from and write to a file
- */
+// fileio.c: read from and write to a file
 
 #include <assert.h>
 #include <errno.h>
@@ -65,57 +63,62 @@
 #define BUFSIZE         8192    /* size of normal write buffer */
 #define SMBUFSIZE       256     /* size of emergency write buffer */
 
-/*
- * The autocommands are stored in a list for each event.
- * Autocommands for the same pattern, that are consecutive, are joined
- * together, to avoid having to match the pattern too often.
- * The result is an array of Autopat lists, which point to AutoCmd lists:
- *
- * first_autopat[0] --> Autopat.next  -->  Autopat.next -->  NULL
- *                      Autopat.cmds       Autopat.cmds
- *                          |                    |
- *                          V                    V
- *                      AutoCmd.next       AutoCmd.next
- *                          |                    |
- *                          V                    V
- *                      AutoCmd.next            NULL
- *                          |
- *                          V
- *                         NULL
- *
- * first_autopat[1] --> Autopat.next  -->  NULL
- *                      Autopat.cmds
- *                          |
- *                          V
- *                      AutoCmd.next
- *                          |
- *                          V
- *                         NULL
- *   etc.
- *
- *   The order of AutoCmds is important, this is the order in which they were
- *   defined and will have to be executed.
- */
+//
+// The autocommands are stored in a list for each event.
+// Autocommands for the same pattern, that are consecutive, are joined
+// together, to avoid having to match the pattern too often.
+// The result is an array of Autopat lists, which point to AutoCmd lists:
+//
+// last_autopat[0]  -----------------------------+
+//                                               V
+// first_autopat[0] --> Autopat.next  -->  Autopat.next -->  NULL
+//                      Autopat.cmds       Autopat.cmds
+//                          |                    |
+//                          V                    V
+//                      AutoCmd.next       AutoCmd.next
+//                          |                    |
+//                          V                    V
+//                      AutoCmd.next            NULL
+//                          |
+//                          V
+//                         NULL
+//
+// last_autopat[1]  --------+
+//                          V
+// first_autopat[1] --> Autopat.next  -->  NULL
+//                      Autopat.cmds
+//                          |
+//                          V
+//                      AutoCmd.next
+//                          |
+//                          V
+//                         NULL
+//   etc.
+//
+//   The order of AutoCmds is important, this is the order in which they were
+//   defined and will have to be executed.
+//
 typedef struct AutoCmd {
-  char_u          *cmd;                 /* The command to be executed (NULL
-                                           when command has been removed) */
-  char nested;                          /* If autocommands nest here */
-  char last;                            /* last command in list */
-  scid_T scriptID;                      /* script ID where defined */
-  struct AutoCmd  *next;                /* Next AutoCmd in list */
+  char_u          *cmd;                 // The command to be executed (NULL
+                                        // when command has been removed)
+  char nested;                          // If autocommands nest here
+  char last;                            // last command in list
+  scid_T scriptID;                      // script ID where defined
+  struct AutoCmd  *next;                // Next AutoCmd in list
 } AutoCmd;
 
 typedef struct AutoPat {
-  char_u          *pat;                 /* pattern as typed (NULL when pattern
-                                           has been removed) */
-  regprog_T       *reg_prog;            /* compiled regprog for pattern */
-  AutoCmd         *cmds;                /* list of commands to do */
-  struct AutoPat  *next;                /* next AutoPat in AutoPat list */
-  int group;                            /* group ID */
-  int patlen;                           /* strlen() of pat */
-  int buflocal_nr;                      /* !=0 for buffer-local AutoPat */
-  char allow_dirs;                      /* Pattern may match whole path */
-  char last;                            /* last pattern for apply_autocmds() */
+  struct AutoPat  *next;                // next AutoPat in AutoPat list; MUST
+                                        // be the first entry
+  char_u          *pat;                 // pattern as typed (NULL when pattern
+                                        // has been removed)
+  regprog_T       *reg_prog;            // compiled regprog for pattern
+  AutoCmd         *cmds;                // list of commands to do
+  int group;                            // group ID
+  int patlen;                           // strlen() of pat
+  int buflocal_nr;                      // !=0 for buffer-local AutoPat
+  char allow_dirs;                      // Pattern may match whole path
+  char last;                            // last pattern for apply_autocmds()
 } AutoPat;
 
 /*
@@ -226,6 +229,15 @@ void filemess(buf_T *buf, char_u *name, char_u *s, int attr)
   msg_scrolled_ign = FALSE;
 }
 
+static AutoPat *last_autopat[NUM_EVENTS] = {
+  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
+};
+
 /*
  * Read lines from file "fname" into the buffer after line "from".
  *
@@ -5528,6 +5540,15 @@ static void au_cleanup(void)
 
       /* remove the pattern if it has been marked for deletion */
       if (ap->pat == NULL) {
+        if (ap->next == NULL) {
+          if (prev_ap == &(first_autopat[(int)event])) {
+            last_autopat[(int)event] = NULL;
+          } else {
+            // this depends on the "next" field being the first in
+            // the struct
+            last_autopat[(int)event] = (AutoPat *)prev_ap;
+          }
+        }
         *prev_ap = ap->next;
         vim_regfree(ap->reg_prog);
         xfree(ap);
@@ -6120,10 +6141,13 @@ static int do_autocmd_event(event_T event, char_u *pat, int nested, char_u *cmd,
       patlen = (int)STRLEN(buflocal_pat);       /*   but not endpat */
     }
 
-    /*
-     * Find AutoPat entries with this pattern.
-     */
-    prev_ap = &first_autopat[(int)event];
+    // Find AutoPat entries with this pattern.  When adding a command it
+    // always goes at or after the last one, so start at the end.
+    if (!forceit && *cmd != NUL && last_autopat[(int)event] != NULL) {
+      prev_ap = &last_autopat[(int)event];
+    } else {
+      prev_ap = &first_autopat[(int)event];
+    }
     while ((ap = *prev_ap) != NULL) {
       if (ap->pat != NULL) {
         /* Accept a pattern when:
@@ -6209,6 +6233,7 @@ static int do_autocmd_event(event_T event, char_u *pat, int nested, char_u *cmd,
         }
         ap->cmds = NULL;
         *prev_ap = ap;
+        last_autopat[(int)event] = ap;
         ap->next = NULL;
         if (group == AUGROUP_ALL)
           ap->group = current_augroup;