[squeak-dev] The Inbox: Files-cmm.125.mcz
Chris Muller
asqueaker at gmail.com
Sun Jun 30 17:19:53 UTC 2013
Hi Levente, I do not know what you mean by DFS and BFS. My claim that
statsForDirectoryTree: "does one useless thing, and does it
inefficiently" is commentary about the _design_, not the
implementation, because it forces me to enumerate an entire directory
even if I don't want to. For example, what if I want to exclude a
".temp" directory's stats from its containing directory's stats? To
do that, I'd have to run #statsForDirectoryTree: twice. That's not
going to be faster..
On Sat, Jun 29, 2013 at 5:15 PM, Levente Uzonyi <leves at elte.hu> wrote:
> On Fri, 28 Jun 2013, commits at source.squeak.org wrote:
>
>> A new version of Files was added to project The Inbox:
>> http://source.squeak.org/inbox/Files-cmm.125.mcz
>>
>> ==================== Summary ====================
>>
>> Name: Files-cmm.125
>> Author: cmm
>> Time: 27 June 2013, 7:24:33.37 pm
>> UUID: 0b00b2c4-3430-442b-a924-72040ff43d73
>> Ancestors: Files-fbs.124
>>
>> FileDirectory>>statsForDirectoryTree: is a prime example of FileDirectory
>> living up to its poor reputation. It does one useless thing, and does it
>> inefficiently. It has no senders, deservedly.
>> Tree-walking operations like gathering stats can be written in
>> apps more generally using directoryTreeDo:.
>
>
> I wouldn't say it's inefficient. It uses BFS (instead of DFS, which is used
> by #directoryTreeDo:entries:), which is somewhat better than DFS, because of
> the way FilePlugin works: you have to iterate over the contents of the whole
> directory if you want to it to be efficient.
> If you use DFS, then the contents of all parent directories up to the root
> will have to be stored in memory during the iteration, while if you use BFS,
> then only the sibling directories (without their contents) or the siblings's
> parents will be in memory.
>
> I made two "new" implementations of #statsForDirectoryTree:. This one
> optimizes memory usage for BFS:
>
> statsForDirectoryTree2: rootedPathName
>
> | dirs files bytes todo |
>
> dirs := files := bytes := 0.
> todo := OrderedCollection with: rootedPathName.
> [ todo isEmpty ] whileFalse: [
> | p |
> p := todo removeFirst.
> self directoryContentsFor: p do: [ :entry |
> entry isDirectory
> ifTrue: [
>
> todo addLast: p , self
> pathNameDelimiter asString , entry name.
> dirs := dirs + 1]
> ifFalse: [
>
> files := files + 1.
> bytes := bytes + entry fileSize ] ]
> ].
> ^{ dirs. files. bytes }
>
> This one uses #directoryTreeDo::
>
> statsForDirectoryTree3: rootedPathName
>
> | dirs files bytes |
>
> dirs := files := bytes := 0.
> (FileDirectory on: rootedPathName) directoryTreeDo: [ :path |
> | entry |
> entry := path last.
> entry isDirectory
> ifTrue: [ dirs := dirs + 1 ]
> ifFalse: [
>
> files := files + 1.
> bytes := bytes + entry fileSize ] ].
> ^{ dirs. files. bytes }
>
> Let's see the numbers:
>
> "Make sure the disk won't be accessed"
> FileDirectory default statsForDirectoryTree: '/usr/'.
> FileDirectory default statsForDirectoryTree: '/usr/'.
> "Run the benchmark"
> #(statsForDirectoryTree: statsForDirectoryTree2: statsForDirectoryTree3:)
> collect: [ :each |
> each -> ((1 to: 5) collect: [ :run |
> Smalltalk garbageCollect.
> [ FileDirectory default perform: each with: '/usr/' ]
> timeToRun ]) ].
>
> {
> #statsForDirectoryTree:->#(6340 6300 6430 6316 6228) .
> #statsForDirectoryTree2:->#(5918 6072 6122 6296 6306) .
> #statsForDirectoryTree3:->#(8576 8374 8470 8506 8228) }
>
> It's a bit noisy (i was too lazy to exit other programs), but the one using
> #directoryTreeDo: seems to be clearly slower than the existing algorithm
> using BFS.
>
>
> Levente
>
>
>>
>> =============== Diff against Files-fbs.124 ===============
>>
>> Item was changed:
>> + ----- Method: FileDirectory>>directoryTreeDo:entries: (in category
>> 'private') -----
>> - ----- Method: FileDirectory>>directoryTreeDo:entries: (in category
>> 'enumeration') -----
>> directoryTreeDo: oneArgBlock entries: entriesCollection
>> "Value oneArgBlock with the path (an OrderedCollection of
>> FileDirectory's) to each DirectoryEntry and the DirectoryEntry itself."
>> self entries do:
>> [ : each |
>> entriesCollection add: each.
>> oneArgBlock value: entriesCollection.
>> each isDirectory ifTrue:
>> [ | subdir |
>> subdir := each asFileDirectory.
>> subdir
>> directoryTreeDo: oneArgBlock
>> entries: entriesCollection ].
>> entriesCollection removeLast ]!
>>
>> Item was removed:
>> - ----- Method: FileDirectory>>statsForDirectoryTree: (in category
>> 'enumeration') -----
>> - statsForDirectoryTree: rootedPathName
>> - "Return the size statistics for the entire directory tree starting
>> at the given root. The result is a three element array of the form: (<number
>> of folders><number of files><total bytes in all files>). This method also
>> serves as an example of how recursively enumerate a directory tree."
>> - "FileDirectory default statsForDirectoryTree: '\smalltalk'"
>> -
>> - | dirs files bytes todo entries p |
>> - dirs := files := bytes := 0.
>> - todo := OrderedCollection with: rootedPathName.
>> - [todo isEmpty] whileFalse: [
>> - p := todo removeFirst.
>> - entries := self directoryContentsFor: p.
>> - entries do: [:entry |
>> - entry isDirectory
>> - ifTrue: [
>> - todo addLast: p , self
>> pathNameDelimiter asString , entry name.
>> - dirs := dirs + 1]
>> - ifFalse: [
>> - files := files + 1.
>> - bytes := bytes + entry
>> fileSize]]].
>> - ^ Array with: dirs with: files with: bytes
>> - !
>>
>>
>>
>
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