[elpa] externals/vlf 32ff2cb 239/310: Add bookkeeping module.

[Stefan Monnier]

branch: externals/vlf
commit 32ff2cb067a4bc31a59064a379eba552cfea17bf
Author: Andrey Kotlarski <m00naticus@gmail.com>
Commit: Andrey Kotlarski <m00naticus@gmail.com>

    Add bookkeeping module.
---
 vlf-tune.el | 159 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 159 insertions(+)

diff --git a/vlf-tune.el b/vlf-tune.el
new file mode 100644
index 0000000..371cf58
--- /dev/null
+++ b/vlf-tune.el
@@ -0,0 +1,159 @@
+;;; vlf-tune.el --- VLF tuning operations  -*- lexical-binding: t -*-
+
+;; Copyright (C) 2014 Free Software Foundation, Inc.
+
+;; Keywords: large files, batch size, performance
+;; Author: Andrey Kotlarski <m00naticus@gmail.com>
+;; URL: https://github.com/m00natic/vlfi
+
+;; This file is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3, or (at your option)
+;; any later version.
+
+;; This file is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs; see the file COPYING.  If not, write to
+;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;;; Commentary:
+;; This package provides wrappers for basic chunk operations that add
+;; time statistics and automatic tuning of `vlf-batch-size' for
+;; optimal performance.
+
+;;; Code:
+
+(defcustom vlf-tune-enabled t
+  "Whether to allow automatic change of batch size.
+If nil, completely disable.  If `stats', maintain measure statistics,
+but don't change batch size.  If t, measure and change."
+  :group 'vlf :type '(choice (const :tag "Enabled" t)
+                             (const :tag "Just statistics" stats)
+                             (const :tag "Disabled" nil)))
+
+(defun vlf-tune-ram-size ()
+  "Try to determine RAM size in bytes."
+  (let* ((free-output (shell-command-to-string "free"))
+         (match-from (string-match "[[:digit:]]+" free-output)))
+    (if match-from
+        (* 1000 (string-to-number (substring free-output match-from
+                                             (match-end 0)))))))
+
+(defcustom vlf-tune-max (let ((ram-size (vlf-tune-ram-size)))
+                          (if ram-size
+                              (/ ram-size 20)
+                            large-file-warning-threshold))
+  "Maximum batch size in bytes when auto tuning."
+  :group 'vlf :type 'integer)
+
+(defcustom vlf-tune-step (/ vlf-tune-max 1000)
+  "Step used for tuning in bytes."
+  :group 'vlf :type 'integer)
+
+(defvar vlf-tune-insert-bps nil
+  "Vector of bytes per second insert measurements.")
+(make-variable-buffer-local 'vlf-tune-insert-bps)
+(put 'vlf-batch-size 'permanent-local t)
+
+(defvar vlf-tune-insert-raw-bps nil
+  "Vector of bytes per second non-decode insert measurements.")
+(make-variable-buffer-local 'vlf-tune-insert-raw-bps)
+(put 'vlf-tune-insert-raw-bps 'permanent-local t)
+
+(defvar vlf-tune-encode-bps nil
+  "Vector of bytes per second encode measurements.")
+(make-variable-buffer-local 'vlf-tune-encode-bps)
+(put 'vlf-tune-encode-bps 'permanent-local t)
+
+(defvar vlf-tune-write-bps nil
+  "Vector of bytes per second write measurements.")
+(make-variable-buffer-local 'vlf-tune-write-bps)
+(put 'vlf-tune-write-bps 'permanent-local t)
+
+(defvar vlf-tune-hexl-bps nil
+  "Vector of bytes per second hexlify measurements.")
+(make-variable-buffer-local 'vlf-tune-hexl-bps)
+(put 'vlf-tune-hexl-bps 'permanent-local t)
+
+(defvar vlf-tune-dehexlify-bps nil
+  "Vector of bytes per second dehexlify measurements.")
+(make-variable-buffer-local 'vlf-tune-dehexlify-bps)
+(put 'vlf-tune-dehexlify-bps 'permanent-local t)
+
+(defun vlf-tune-initialize-measurement ()
+  "Initialize measurement vector."
+  (make-vector (1- (/ vlf-tune-max vlf-tune-step)) '(0 . 0)))
+
+(defmacro vlf-tune-add-measurement (vec size time)
+  "Add at an appropriate position in VEC new SIZE TIME measurement.
+VEC is a vector of (mean time . count) elements ordered by size."
+  `(when vlf-tune-enabled
+     (or ,vec (setq ,vec (vlf-tune-initialize-measurement)))
+     (let* ((idx (max 0 (1- (min (round ,size vlf-tune-step) ;closest index
+                                 (/ vlf-tune-max vlf-tune-step)))))
+            (existing (aref ,vec idx)))
+       (aset ,vec idx (let ((count (1+ (cdr existing)))) ;recalculate mean
+                        (cons (/ (+ (* (1- count) (car existing))
+                                    (/ ,size ,time))
+                                 count)
+                              count))))))
+
+(defmacro vlf-time (&rest body)
+  "Get timing consed with result of BODY execution."
+  `(let ((time (float-time))
+         (result (progn ,@body)))
+     (cons (- (float-time) time) result)))
+
+(defun vlf-tune-insert-file-contents (start end)
+  "Extract decoded file bytes START to END and save time it takes."
+  (let ((result (vlf-time (insert-file-contents buffer-file-name
+                                                nil start end))))
+    (vlf-tune-add-measurement vlf-tune-insert-bps
+                              (- end start) (car result))
+    (cdr result)))
+
+(defun vlf-tune-insert-file-contents-literally (start end)
+  "Insert raw file bytes START to END and save time it takes."
+  (let ((result (vlf-time (insert-file-contents-literally
+                           buffer-file-name nil start end))))
+    (vlf-tune-add-measurement vlf-tune-insert-raw-bps
+                              (- end start) (car result))
+    (cdr result)))
+
+(defun vlf-tune-encode-length (start end)
+  "Get length of encoded region START to END and save time it takes."
+  (let ((result (vlf-time (length (encode-coding-region
+                                   start end
+                                   buffer-file-coding-system t)))))
+    (vlf-tune-add-measurement vlf-tune-encode-bps
+                              (- end start) (car result))
+    (cdr result)))
+
+(defun vlf-tune-write (start end append visit size)
+  "Save buffer and save time it takes.
+START, END, APPEND, VISIT have same meaning as in `write-region'.
+SIZE is number of bytes that are saved."
+  (let ((time (car (write-region start end buffer-file-name
+                                 append visit))))
+    (vlf-tune-add-measurement vlf-tune-write-bps size time)))
+
+(defun vlf-tune-hexlify ()
+  "Activate `hexl-mode' and save time it takes."
+  (let ((time (car (vlf-time (hexl-mode)))))
+    (vlf-tune-add-measurement vlf-tune-hexl-bps
+                              hexl-max-address time)))
+
+(defun vlf-tune-dehexlify ()
+  "Exit `hexl-mode' and save time it takes."
+  (let ((time (car (vlf-time (hexl-mode-exit)))))
+    (vlf-tune-add-measurement vlf-tune-dehexlify-bps
+                              hexl-max-address time)))
+
+(provide 'vlf-tune)
+
+;;; vlf-tune.el ends here