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authorDave Smith <dizzyd@dizzyd.com>2011-10-25 23:59:50 -0600
committerTuncer Ayaz <tuncer.ayaz@gmail.com>2011-10-26 23:16:36 +0200
commit17616d1078063ea0748d009e3a111c4b615262e8 (patch)
treed714ece6f68f8ee1085c8b7edbcabe7385b70c32 /src
parentb65d5904f555874e24a4610ea63d8c10ecf62448 (diff)
Overhaul environment expansion for better performance
The introduction of setup_env as a global concept caused the rebar_port_compiler implementation to start getting called a LOT. The expansion of environment variables that happens in the port compiler was O(n^n), which means you could see upwards of 80k invocations of lists:foldl on a single app "./rebar clean". This commit reworks the expansion to be O(n^2), and reduces the running time for the same operation by 60%+. On a large project like Riak, the end result is that a build went from 200 seconds to 73.
Diffstat (limited to 'src')
-rw-r--r--src/rebar_port_compiler.erl69
-rw-r--r--src/rebar_utils.erl18
2 files changed, 53 insertions, 34 deletions
diff --git a/src/rebar_port_compiler.erl b/src/rebar_port_compiler.erl
index a473fa5..1f5ebac 100644
--- a/src/rebar_port_compiler.erl
+++ b/src/rebar_port_compiler.erl
@@ -290,38 +290,51 @@ merge_each_var([{Key, Value} | Rest], Vars) ->
%% for every other key until no further expansions are possible.
%%
expand_vars_loop(Vars) ->
- expand_vars_loop(Vars, 10).
+ expand_vars_loop(Vars, [], dict:from_list(Vars), 10).
-expand_vars_loop(_, 0) ->
+expand_vars_loop(_Pending, _Recurse, _Vars, 0) ->
?ABORT("Max. expansion reached for ENV vars!\n", []);
-expand_vars_loop(Vars0, Count) ->
- Vars = lists:foldl(fun({Key, Value}, Acc) ->
- expand_vars(Key, Value, Acc)
- end,
- Vars0, Vars0),
- case orddict:from_list(Vars) of
- Vars0 ->
- Vars0;
- _ ->
- expand_vars_loop(Vars, Count-1)
+expand_vars_loop([], [], Vars, _Count) ->
+ lists:keysort(1, dict:to_list(Vars));
+expand_vars_loop([], Recurse, Vars, Count) ->
+ expand_vars_loop(Recurse, [], Vars, Count-1);
+expand_vars_loop([{K, V} | Rest], Recurse, Vars, Count) ->
+ %% Identify the variables that need expansion in this value
+ case re:run(V, "\\\${?(\\w+)}?", [global, {capture, all_but_first, list}]) of
+ {match, Matches} ->
+ %% Identify the unique variables that need to be expanded
+ UniqueMatches = lists:usort([M || [M] <- Matches]),
+
+ %% For each variable, expand it and return the final value. Note that
+ %% if we have a bunch of unresolvable variables, nothing happens and
+ %% we don't bother attempting further expansion
+ case expand_keys_in_value(UniqueMatches, V, Vars) of
+ V ->
+ %% No change after expansion; move along
+ expand_vars_loop(Rest, Recurse, Vars, Count);
+ Expanded ->
+ %% Some expansion occurred; move to next k/v but revist
+ %% this value in the next loop to check for further expansion
+ NewVars = dict:store(K, Expanded, Vars),
+ expand_vars_loop(Rest, [{K, Expanded} | Recurse], NewVars, Count)
+ end;
+
+ nomatch ->
+ %% No values in this variable need expansion; move along
+ expand_vars_loop(Rest, Recurse, Vars, Count)
end.
-%%
-%% Expand all OTHER references to a given K/V pair
-%%
-expand_vars(Key, Value, Vars) ->
- lists:foldl(
- fun({AKey, AValue}, Acc) ->
- NewValue = case AKey of
- Key ->
- AValue;
- _ ->
- rebar_utils:expand_env_variable(AValue,
- Key, Value)
- end,
- [{AKey, NewValue} | Acc]
- end,
- [], Vars).
+expand_keys_in_value([], Value, _Vars) ->
+ Value;
+expand_keys_in_value([Key | Rest], Value, Vars) ->
+ NewValue = case dict:find(Key, Vars) of
+ {ok, KValue} ->
+ rebar_utils:expand_env_variable(Value, Key, KValue);
+ error ->
+ Value
+ end,
+ expand_keys_in_value(Rest, NewValue, Vars).
+
expand_command(TmplName, Env, InFiles, OutFile) ->
Cmd0 = proplists:get_value(TmplName, Env),
diff --git a/src/rebar_utils.erl b/src/rebar_utils.erl
index 84567ba..88c0c25 100644
--- a/src/rebar_utils.erl
+++ b/src/rebar_utils.erl
@@ -186,12 +186,18 @@ expand_code_path() ->
%% The end of form $FOO is delimited with whitespace or eol
%%
expand_env_variable(InStr, VarName, RawVarValue) ->
- ReOpts = [global, {return, list}],
- VarValue = re:replace(RawVarValue, "\\\\", "\\\\\\\\", ReOpts),
- R1 = re:replace(InStr, "\\\$" ++ VarName ++ "\\s", VarValue ++ " ",
- [global]),
- R2 = re:replace(R1, "\\\$" ++ VarName ++ "\$", VarValue),
- re:replace(R2, "\\\${" ++ VarName ++ "}", VarValue, ReOpts).
+ case string:chr(InStr, $$) of
+ 0 ->
+ %% No variables to expand
+ InStr;
+ _ ->
+ ReOpts = [global, {return, list}],
+ VarValue = re:replace(RawVarValue, "\\\\", "\\\\\\\\", [global]),
+ %% Use a regex to match/replace:
+ %% $FOO\s | ${FOO} | $FOO eol
+ RegEx = io_lib:format("\\\$(~s(\\s|$)|{~s})", [VarName, VarName]),
+ re:replace(InStr, RegEx, VarValue ++ "\\2", ReOpts)
+ end.
%% ====================================================================