Add an option for completely disabling command history, and add documentation

autoload/ale/engine.vim

@@ -458,7 +458,11 @@ function! s:RunJob(options) abort
         \}
     endif
 
-    call ale#history#Add(l:buffer, l:status, l:job_id, l:command)
+    if g:ale_history_enabled
+        call ale#history#Add(l:buffer, l:status, l:job_id, l:command)
+    else
+        let g:ale_buffer_info[l:buffer].history = []
+    endif
 endfunction
 
 " Determine which commands to run for a link in a command chain, or

doc/ale.txt

@@ -186,6 +186,19 @@ g:ale_enabled                                                   *g:ale_enabled*
   the |ALEToggle| command, which changes this option.
 
 
+g:ale_history_enabled                                   *g:ale_history_enabled*
+
+  Type: |Number|
+  Default: `1`
+
+  When set to `1`, ALE will remember the last few commands which were run
+  for every buffer which is open. This information can be viewed with the
+  |ALEInfo| command. The size of the buffer can be controlled with the
+  |g:ale_max_buffer_history_size| option.
+
+  This option can be disabled if storing a command history is not desired.
+
+
 g:ale_keep_list_window_open                       *g:ale_keep_list_window_open*
 
   Type: |Number|
@@ -311,6 +324,19 @@ g:ale_linters                                                   *g:ale_linters*
   let g:ale_linters = {'c': 'all'}
 <
 
+g:ale_max_buffer_history_size                   *g:ale_max_buffer_history_size*
+
+  Type: |Number|
+  Default: `20`
+
+  This setting controls the maximum number of commands which will be stored in
+  the command history used for |ALEInfo|. Command history will be rotated in
+  a FIFO manner. If set to a number <= 0, then the history will be
+  continuously set to an empty |List|.
+
+  History can be disabled completely with |g:ale_history_enabled|.
+
+
 g:ale_open_list                                               *g:ale_open_list*
 
   Type: |Number|

plugin/ale.vim

@@ -134,6 +134,9 @@ let g:ale_warn_about_trailing_whitespace =
 " A flag for controlling the maximum size of the command history to store.
 let g:ale_max_buffer_history_size = get(g:, 'ale_max_buffer_history_size', 20)
 
+" A flag for enabling or disabling the command history.
+let g:ale_history_enabled = get(g:, 'ale_history_enabled', 1)
+
 function! s:ALEInitAuGroups() abort
     augroup ALERunOnTextChangedGroup
         autocmd!

test/test_history_saving.vader

@@ -16,6 +16,7 @@ Before:
   \})
 
 After:
+  let g:ale_history_enabled = 1
   unlet g:history
   let g:ale_buffer_info = {}
   let g:ale_max_buffer_history_size = 20
@@ -40,6 +41,16 @@ Execute(History should be set when commands are run):
   " The Job ID will change each time, but we can check the type.
   AssertEqual type(1), type(g:history[0].job_id)
 
+Execute(History should be not set when disabled):
+  AssertEqual 'foobar', &filetype
+
+  let g:ale_history_enabled = 0
+
+  call ale#Lint()
+  call ale#engine#WaitForJobs(2000)
+
+  AssertEqual 0, len(g:ale_buffer_info[bufnr('%')].history)
+
 Execute(History items should be popped after going over the max):
   let g:ale_buffer_info[1] = {
   \ 'history': map(range(20), '{''status'': ''started'', ''job_id'': v:val, ''command'': ''foobar''}'),