| .gitignore | ||
| README.org | ||
| vlf-base.el | ||
| vlf-ediff.el | ||
| vlf-follow.el | ||
| vlf-integrate.el | ||
| vlf-occur.el | ||
| vlf-search.el | ||
| vlf-write.el | ||
| vlf.el | ||
View Large Files
Emacs minor mode that allows viewing, editing, searching and comparing large files in batches. Batch size can be adjusted on the fly and bounds the memory that is to be used for operations on the file. This way multiple large files (like terabytes or whatever) can be instantly and simultaneously accessed without swapping and degraded performance.
This is development version of the GNU ELPA VLF package. Here's what it offers in a nutshell:
- regular expression search on whole file (in constant memory determined by current batch size)
- chunk editing (save is immediate if size hasn't changed, done in constant memory determined by current batch size otherwise)
- Occur like indexing
- options to jump to beginning, end or arbitrary file chunk
- ability to jump/insert given number of batches at once
- newly added content is acknowledged if file has changed size meanwhile
- automatic scrolling of batches
- as it's a minor mode, font locking and functionality of the respective major mode is also present
- by batch Ediff comparison
- can be added as option to automatically open large files
- smooth integration with hexl-mode
- works with TRAMP so accessing network files is fine
GNU Emacs 23 and 24 are supported.
Overview and tips
M-x vlf PATH-TO-FILE
Unicode
Emacs' Unicode support is leveraged so you'll not see bare bytes but characters decoded as if file is normally opened. This holds for editing, search, indexing and comparison.
32-bit GNU Emacs
Regular Emacs integers are used, so if you use 32-bit Emacs without bignum support, VLF will not work with files over 512 MB (maximum integer value).
Memory control
vlf-batch-size bounds the memory used for all operations.
Detail usage
Applicability
To have vlf offered as choice when opening large files:
(require 'vlf-integrate)
You can control when vlf-mode is invoked or offered with the vlf-application customization option. By default it will offer VLF when opening large files. There are also options to never use it (you can still call vlf command explicitly); to use it without asking for large files or to invoke it on all files. Here's example setup such that vlf-mode automatically launches for large files:
(custom-set-variables '(vlf-application 'dont-ask))
Disable for specific mode
To disable automatic usage of VLF for a major mode, add it to vlf-forbidden-modes-list.
Disable for specific function
To disable automatic usage of VLF for a function, for example named func defined in file file.el:
(vlf-disable-for-function func "file")
Keymap
All VLF operations are grouped under the C-c C-v prefix by default. Here's example how to add another prefix (C-x v):
(eval-after-load "vlf" '(define-key vlf-prefix-map "\C-xv" vlf-mode-map))
Control batch size
Use M-x vlf-set-batch-size to change batch size and update chunk immediately.
C-c C-v + and C-c C-v - control current batch size by factors of 2.
Move around
Scrolling automatically triggers move to previous or next chunk at the beginning or end respectively of the current one.
C-c C-v n and C-c C-v p move batch by batch. With positive prefix argument they move prefix number of batches. With negative - append prefix number of batches.
C-c C-v SPC displays batch starting from current point.
C-c C-v [ and C-c C-v ] take you to the beginning and end of file respectively.
C-c C-v j jumps to given chunk. To see where you are in file and how many chunks there are (using the current batch size), look at the parenthesized part of the buffer name, batch size is also indicated at the end.
Follow point
Continuous chunk recenter around point in current buffer can be toggled with C-c C-v f.
Search whole file
C-c C-v s and C-c C-v r search forward and backward respectively over the whole file. This is done batch by batch so if you have really huge file - you'd better set somewhat bigger batch size beforehand.
Occur over whole file
C-c C-v o builds index for given regular expression just like M-x occur. It does so batch by batch over the whole file. Note that even if you prematurely stop it with C-g, it will still show index of what's found so far.
Jump to line
C-c C-v l jumps to given line in file. This is done by searching from the beginning, so again the bigger current batch size, probably the quicker. With negative argument, lines are counted from the end of file.
Edit and save
If editing doesn't change size of the chunk, only this chunk is saved. Otherwise the remaining part of the file is adjusted batch by batch, so again you'd better have bigger current batch size.
By batch Ediff
Use M-x vlf-ediff-files and M-x vlf-ediff-buffers to compare files/buffers batch by batch (batch size is queried in case of files or taken from the first buffer in case of buffers). Moving after the last difference in current chunk searches for following one with difference. The other way around if looking for difference before the first one.
Extending
Move hooks
A couple of hooks are run whenever updating chunk: vlf-before-chunk-update and vlf-after-chunk-update.
Batch move hooks
Some operations may trigger multiple chunk moves. There are a couple of hooks that run in such cases: vlf-before-batch-functions and vlf-after-batch-functions. They are passed one argument which specifies type of operation that runs. Possible values are the symbols: write, ediff, occur, search and goto-line.