refactor(api): use an arena for nvim_buf_get_lines and buffer updates

Refactor some earlier "temporary Array" code in buffer_updates.c to use
the modern style of MAXSIZE_TEMP_ARRAY and ADD_C

1 files changed, 44 insertions, 53 deletions

diff --git a/src/nvim/buffer_updates.c b/src/nvim/buffer_updates.c
index a91a890d0e..1a02ac78d7 100644
--- a/src/nvim/buffer_updates.c
+++ b/src/nvim/buffer_updates.c
@@ -55,36 +55,33 @@ bool buf_updates_register(buf_T *buf, uint64_t channel_id, BufUpdateCallbacks cb
   kv_push(buf->update_channels, channel_id);
 
   if (send_buffer) {
-    Array args = ARRAY_DICT_INIT;
-    args.size = 6;
-    args.items = xcalloc(args.size, sizeof(Object));
+    MAXSIZE_TEMP_ARRAY(args, 6);
 
     // the first argument is always the buffer handle
-    args.items[0] = BUFFER_OBJ(buf->handle);
-    args.items[1] = INTEGER_OBJ(buf_get_changedtick(buf));
+    ADD_C(args, BUFFER_OBJ(buf->handle));
+    ADD_C(args, INTEGER_OBJ(buf_get_changedtick(buf)));
     // the first line that changed (zero-indexed)
-    args.items[2] = INTEGER_OBJ(0);
+    ADD_C(args, INTEGER_OBJ(0));
     // the last line that was changed
-    args.items[3] = INTEGER_OBJ(-1);
-    Array linedata = ARRAY_DICT_INIT;
+    ADD_C(args, INTEGER_OBJ(-1));
 
     // collect buffer contents
 
     STATIC_ASSERT(SIZE_MAX >= MAXLNUM, "size_t smaller than MAXLNUM");
     size_t line_count = (size_t)buf->b_ml.ml_line_count;
 
-    if (line_count >= 1) {
-      linedata.size = line_count;
-      linedata.items = xcalloc(line_count, sizeof(Object));
-
-      buf_collect_lines(buf, line_count, 1, 0, true, &linedata, NULL, NULL);
+    Array linedata = ARRAY_DICT_INIT;
+    Arena arena = ARENA_EMPTY;
+    if (line_count > 0) {
+      linedata = arena_array(&arena, line_count);
+      buf_collect_lines(buf, line_count, 1, 0, true, &linedata, NULL, &arena);
     }
 
-    args.items[4] = ARRAY_OBJ(linedata);
-    args.items[5] = BOOLEAN_OBJ(false);
+    ADD_C(args, ARRAY_OBJ(linedata));
+    ADD_C(args, BOOLEAN_OBJ(false));
 
     rpc_send_event(channel_id, "nvim_buf_lines_event", args);
-    api_free_array(args);  // TODO(bfredl): no
+    arena_mem_free(arena_finish(&arena));
   } else {
     buf_updates_changedtick_single(buf, channel_id);
   }
@@ -176,13 +173,10 @@ void buf_updates_unload(buf_T *buf, bool can_reload)
     }
 
     if (thecb != LUA_NOREF) {
-      Array args = ARRAY_DICT_INIT;
-      Object items[1];
-      args.size = 1;
-      args.items = items;
+      MAXSIZE_TEMP_ARRAY(args, 1);
 
       // the first argument is always the buffer handle
-      args.items[0] = BUFFER_OBJ(buf->handle);
+      ADD_C(args, BUFFER_OBJ(buf->handle));
 
       TEXTLOCK_WRAP({
         nlua_call_ref(thecb, keep ? "reload" : "detach", args, false, NULL);
@@ -219,45 +213,43 @@ void buf_updates_send_changes(buf_T *buf, linenr_T firstline, int64_t num_added,
   // if one the channels doesn't work, put its ID here so we can remove it later
   uint64_t badchannelid = 0;
 
+  Arena arena = ARENA_EMPTY;
+  Array linedata = ARRAY_DICT_INIT;
+  if (num_added > 0 && kv_size(buf->update_channels)) {
+    STATIC_ASSERT(SIZE_MAX >= MAXLNUM, "size_t smaller than MAXLNUM");
+    linedata = arena_array(&arena, (size_t)num_added);
+    buf_collect_lines(buf, (size_t)num_added, firstline, 0, true, &linedata,
+                      NULL, &arena);
+  }
+
   // notify each of the active channels
   for (size_t i = 0; i < kv_size(buf->update_channels); i++) {
     uint64_t channelid = kv_A(buf->update_channels, i);
 
     // send through the changes now channel contents now
-    Array args = ARRAY_DICT_INIT;
-    args.size = 6;
-    args.items = xcalloc(args.size, sizeof(Object));
+    MAXSIZE_TEMP_ARRAY(args, 6);
 
     // the first argument is always the buffer handle
-    args.items[0] = BUFFER_OBJ(buf->handle);
+    ADD_C(args, BUFFER_OBJ(buf->handle));
 
     // next argument is b:changedtick
-    args.items[1] = send_tick ? INTEGER_OBJ(buf_get_changedtick(buf)) : NIL;
+    ADD_C(args, send_tick ? INTEGER_OBJ(buf_get_changedtick(buf)) : NIL);
 
     // the first line that changed (zero-indexed)
-    args.items[2] = INTEGER_OBJ(firstline - 1);
+    ADD_C(args, INTEGER_OBJ(firstline - 1));
 
     // the last line that was changed
-    args.items[3] = INTEGER_OBJ(firstline - 1 + num_removed);
+    ADD_C(args, INTEGER_OBJ(firstline - 1 + num_removed));
 
     // linedata of lines being swapped in
-    Array linedata = ARRAY_DICT_INIT;
-    if (num_added > 0) {
-      STATIC_ASSERT(SIZE_MAX >= MAXLNUM, "size_t smaller than MAXLNUM");
-      linedata.size = (size_t)num_added;
-      linedata.items = xcalloc((size_t)num_added, sizeof(Object));
-      buf_collect_lines(buf, (size_t)num_added, firstline, 0, true, &linedata,
-                        NULL, NULL);
-    }
-    args.items[4] = ARRAY_OBJ(linedata);
-    args.items[5] = BOOLEAN_OBJ(false);
+    ADD_C(args, ARRAY_OBJ(linedata));
+    ADD_C(args, BOOLEAN_OBJ(false));
     if (!rpc_send_event(channelid, "nvim_buf_lines_event", args)) {
       // We can't unregister the channel while we're iterating over the
       // update_channels array, so we remember its ID to unregister it at
       // the end.
       badchannelid = channelid;
     }
-    api_free_array(args);  // TODO(bfredl): no
   }
 
   // We can only ever remove one dead channel at a time. This is OK because the
@@ -268,38 +260,37 @@ void buf_updates_send_changes(buf_T *buf, linenr_T firstline, int64_t num_added,
     buf_updates_unregister(buf, badchannelid);
   }
 
-  // notify each of the active channels
+  // callbacks don't use linedata
+  arena_mem_free(arena_finish(&arena));
+
+  // notify each of the active callbacks
   size_t j = 0;
   for (size_t i = 0; i < kv_size(buf->update_callbacks); i++) {
     BufUpdateCallbacks cb = kv_A(buf->update_callbacks, i);
     bool keep = true;
     if (cb.on_lines != LUA_NOREF && (cb.preview || !cmdpreview)) {
-      Array args = ARRAY_DICT_INIT;
-      Object items[8];
-      args.size = 6;  // may be increased to 8 below
-      args.items = items;
+      MAXSIZE_TEMP_ARRAY(args, 8);  // 6 or 8 used
 
       // the first argument is always the buffer handle
-      args.items[0] = BUFFER_OBJ(buf->handle);
+      ADD_C(args, BUFFER_OBJ(buf->handle));
 
       // next argument is b:changedtick
-      args.items[1] = send_tick ? INTEGER_OBJ(buf_get_changedtick(buf)) : NIL;
+      ADD_C(args, send_tick ? INTEGER_OBJ(buf_get_changedtick(buf)) : NIL);
 
       // the first line that changed (zero-indexed)
-      args.items[2] = INTEGER_OBJ(firstline - 1);
+      ADD_C(args, INTEGER_OBJ(firstline - 1));
 
       // the last line that was changed
-      args.items[3] = INTEGER_OBJ(firstline - 1 + num_removed);
+      ADD_C(args, INTEGER_OBJ(firstline - 1 + num_removed));
 
       // the last line in the updated range
-      args.items[4] = INTEGER_OBJ(firstline - 1 + num_added);
+      ADD_C(args, INTEGER_OBJ(firstline - 1 + num_added));
 
       // byte count of previous contents
-      args.items[5] = INTEGER_OBJ((Integer)deleted_bytes);
+      ADD_C(args, INTEGER_OBJ((Integer)deleted_bytes));
       if (cb.utf_sizes) {
-        args.size = 8;
-        args.items[6] = INTEGER_OBJ((Integer)deleted_codepoints);
-        args.items[7] = INTEGER_OBJ((Integer)deleted_codeunits);
+        ADD_C(args, INTEGER_OBJ((Integer)deleted_codepoints));
+        ADD_C(args, INTEGER_OBJ((Integer)deleted_codeunits));
       }
 
       Object res;