logviewer-mode of emacs

近来经常需要查看某些 Log 文件，当用 Emacs 打开这些巨大的 Log 文件的时候，总是需要等待较长的时间，且没有什么语法高亮， 不能让自己感兴趣的区域来吸引眼球。

Google 了一下，发现没有很合适的 log viewer ， 有一个 log4j， 试用了一下，效果不好，还有一个纯粹的 viewer-mode ， 也不太好。 于是自己动手写了一个，主要特色有：

Log 语法高亮

与 VIM 打开 /var/log/messages 时的效果类似。

打开大文件时自动分割成若干小文件，并逐片打开和显示这个功能在打开大文件时候比较好用，该状态下，可通过 n 和 p 来在分片中切换 。

(未完成)Log 级别过滤该功能尚未添加，主要是想可以对 log 进行过滤，比如只显示 ERROR 以上级别的 log 等， 现在对这个功能的需求不大，等以后再加上吧。

代码如下（使用方法参考代码注释）:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; logviewer.el --- Simple log viewer.
;;
;; Copyright (C) 2011, Yang, Ying-chao
;;
;; Author:        Yang, Ying-chao <yangyingchao@gmail.com>
;;
;; This file is NOT part of GNU Emacs.
;;
;; This program 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 2
;; of the License, or (at your option) any later version.
;;
;; This program 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 this program; if not, write to the Free Software
;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
;;
;; Commentary:
;;
;;   This is a simple log viewer, with syntax highlight.
;;
;;   To use logviewer, you should put logviewer.el into the top of load-path
;; of emacs, the add following lines into your .emacs:
;; (require 'logviewer)
;;
;;   When log files are huge, it will try to split huge logs into small ones
;; to speed up loading. In that case, you can press "n" & "p" to go to next
;; part (or previous part) to the log file. You can custom variable
;; logviewer-split-line to proper number to control the size of the slice of
;; huge file.
;;
;; TODO:
;;   Add support of log filtering, ie, show logs whos level is higher than
;; some specified one.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Code
;; custom hooks
(defvar logviewer-mode-hook nil)

;; default mode map, really simple
(defvar logviewer-mode-map
(let ((logviewer-mode-map (make-keymap)))
(define-key logviewer-mode-map "n"
(lambda () (interactive) (logviewer-next-file t)))
(define-key logviewer-mode-map "p"
(lambda () (interactive) (logviewer-next-file nil)))
logviewer-mode-map)
"Keymap for PS major mode")

(defvar logviewer-indent-width 4)

(defvar logviewer-font-lock-keywords
`(
;; Date & time.
(,(rx line-start
(*? not-newline) (+ digit) ":" (+ digit) ":" (+ digit)
(? "." (+ digit)))
. font-lock-builtin-face)
(,(rx symbol-start
(group (*? not-newline) (+ digit) ":" (+ digit) ":" (+ digit) (? "." (+ digit)))
(1+ space) (group (1+ (or alnum "-" "_"  blank))) (? "["(* digit) "]")":")
(1 font-lock-builtin-face) (2 font-lock-variable-name-face))
(,(rx symbol-start
(group (or "ERROR" "FATAL" "error" "fatal" )) ":"
(group (+ (*? not-newline))) line-end)
(1 font-lock-warning-face) (2 font-lock-comment-face))
(,(rx symbol-start
(group (or "info" "INFO" )) ":"
(group (+ (*? not-newline))) line-end)
(1 font-lock-function-name-face) (2 font-lock-doc-face))
(,(rx symbol-start
(group (or "DEBUG" "debug" )) ":"
(group (+ (*? not-newline))) line-end)
(1 font-lock-keyword-face) (2 font-lock-string-face))
)
)

(defvar logviewer-mode-syntax-table (make-syntax-table)
"Syntax table for Logviewer mode")
;; (modify-syntax-entry ?( "()" logviewer-mode-syntax-table)
;;                      (modify-syntax-entry ?) ")("
;;                      logviewer-mode-syntax-table)

(defvar logviewer-imenu-expressions
'((nil "^\\(?:[fF]unction\\|Add-Class\\)\\s-+\\([-a-z0-9A-Z_^:.]+\\)[^-a-z0-9A-Z_^:.]" 1))
"alist of regexp identifying the start of logviewer definitions"
)

(defvar logviewer-split-line 50000 "Lines when trying to split files.")
(defvar Logviewer-current-file nil
"Log file viewed by logviewer")

(defun logviewer-process-sentinel (process event)
"description"
(when (memq (process-status process) '(signal exit))
(let* ((exit-status       (process-exit-status process))
(command           (process-command process))
(source-buffer     (process-buffer process))
)

(condition-case err
(delete-process process)
(error
(let ((err-str (format "Error in process sentinel: %s"
(error-message-string err))))
(message err-str)))))))

;;;; Overrite function provied by Emacs itself.
(defun abort-if-file-too-large (size op-type filename)
"If file SIZE larger than `large-file-warning-threshold', allow user to abort.
OP-TYPE specifies the file operation being performed (for message to user)."
(let* ((re-log-str (rx (or "LOG" "log" "Log")))
(log-cache (expand-file-name "~/.emacs.d/log_cache"))
(cur-file nil)
(process nil)
(filename-base (file-name-sans-extension
(file-name-nondirectory filename)))
(out-file-prefix (format "%s/%s" log-cache filename-base)))
(if (and  large-file-warning-threshold size
(> size large-file-warning-threshold))
(if (string-match re-log-str filename) ;; This is logfile.
(if (y-or-n-p
(format "LogFile %s is large (%dMB), really %s? "
(file-name-nondirectory filename)
(/ size 1048576) op-type))
(if (and (string= op-type "open")
(executable-find "split"))
(progn
(if (file-exists-p log-cache)
nil
(mkdir log-cache t))
(setq Logviewer-current-file
(format "%s000" out-file-prefix))

(message (format "%s*" out-file-prefix))
(call-process-shell-command "rm" nil "*Messages*" nil
"-rf"
(format "%s*" out-file-prefix))
(setq process
(start-process "Split-process" "*Messages*"
"split"  "--suffix-length=3"
"-d" "-l"
(format "%s" logviewer-split-line)
(expand-file-name filename)
out-file-prefix))
(set-process-sentinel process
'logviewer-process-sentinel)

(while (not (file-exists-p Logviewer-current-file))
(sleep-for 0.5))

(set-buffer (get-buffer-create filename-base))
(toggle-read-only 0)
(erase-buffer)
(insert-file-contents Logviewer-current-file nil)
(switch-to-buffer filename-base)
(toggle-read-only 1)
(add-to-list 'recentf-list filename)
(logviewer-mode)
(error "See this instead")
)
nil
(error "Aborted")
)
(when  (not (y-or-n-p
(format "YC: File %s is large (%dMB), really %s? "
(file-name-nondirectory filename)
(/ size 1048576) op-type)))
(error "Aborted"))
)
)
)))

(defun get-next-file (cc)
"Get next file, or previous file.
if direc = t, it returns next file, or it returns previous file"
(let ((filename-pre nil)
(filename-sub nil)
(filename Logviewer-current-file)
(filename-sub-num 0)
(sub-len 0)
(new-seq 0)
(fmt "")
(pre-rx (rx line-start (group (+? not-newline))
(group (+ digit)) line-end)))
(if (string-match pre-rx filename)
(progn
(setq filename-pre (match-string 1 filename))
(setq filename-sub (match-string 2 filename))
(setq sub-len (length filename-sub))
(if cc
(setq new-seq (1+ (string-to-number filename-sub)))
(setq new-seq (1- (string-to-number filename-sub)))
)
(format (format "%%s%%0%dd" sub-len)
filename-pre new-seq))
(error "Failed to parse filename"))))

(defun logviewer-next-file (dir)
"view next/previous file"
(let ((next-file nil))
(if (string-match "log_cache" Logviewer-current-file)
(progn
(setq next-file (get-next-file dir))
(if (file-exists-p next-file)
(progn
(message (format "Now viewing: %s" next-file))
(toggle-read-only 0)
(erase-buffer)
(insert-file-contents next-file nil)
(setq Logviewer-current-file next-file)
(toggle-read-only 1))
(progn
(let ((msg nil))
(if dir
(setq msg (concat "Tail of log reached. File "
next-file " does not exist!" ))
(setq msg (concat "Head of log reached. File "
next-file " does not exist!" )))
(error msg))
)
))
(error "This is the whole file"))))

(defun logviewer-setup-imenu ()
"Installs logviewer-imenu-expression."
(require 'imenu t)
;; imenu doc says these 3 are buffer-local by default
(setq imenu-generic-expression logviewer-imenu-expressions)
(imenu-add-menubar-index)
)

(defun logviewer-mode ()
"Major mode for editing Logviewer files"
(interactive)
(kill-all-local-variables)
(setq major-mode 'logviewer-mode)
(setq mode-name "logviewer")
(set-syntax-table logviewer-mode-syntax-table)
(use-local-map logviewer-mode-map)
(set (make-local-variable 'font-lock-defaults)
'(logviewer-font-lock-keywords))
(toggle-read-only t)
(if (not Logviewer-current-file)
(setq Logviewer-current-file (buffer-file-name)))
(run-hooks 'logviewer-mode-hook))

(add-to-list 'auto-mode-alist '("\\.log\\'" .
logviewer-mode))
(provide 'logviewer)