Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

deep hash code for byte[] and other array in tuple #746

Open
wants to merge 4 commits into
base: master
Choose a base branch
from
Open

deep hash code for byte[] and other array in tuple #746

Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
7870b26
use java.util.Arrays.deepHashCode() instead of List.hashCode() for tuple
xiaokang Jan 7, 2013
03c130a
Merge branch 'master' of https://github.com/nathanmarz/storm into sto…
xiaokang Nov 14, 2013
b846ea1
implement deep-hash-code in clojure
xiaokang Nov 14, 2013
92e30be
fix according to review comments
xiaokang Nov 16, 2013
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
34 changes: 33 additions & 1 deletion storm-core/src/clj/backtype/storm/tuple.clj
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,5 +4,37 @@

(bootstrap)

(def ARRAY-TYPES
#{
(type (to-array []))
(type (byte-array 0))
(type (char-array 0))
(type (short-array 0))
(type (int-array 0))
(type (long-array 0))
(type (float-array 0))
(type (double-array 0))
(type (boolean-array 0))
})

(declare hash-code)

(defn deep-hash-code [alist]
"deep hash code based on array/list content.
it's the same as java.util.Arrays.deepHashCode(),
but without convert a list to array to avoid copy.

use unchecked-* to make sure use int instead of long."
(reduce
Copy link
Owner

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

We can make this code much faster by not doing the reduce (which is constantly boxing and unboxing the numbers) and instead iterating through the list. It's doable in Clojure, though I'm ok with writing this code in Java and then calling it from here.

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Do you mean ".intValue" and "+" cause constantly boxing and unboxing the numbers? Can we use unchecked-add-int and unchecked-multiply-int to avoid boxing and unboxing?
I tested with unchecked-* and it's 10% faster than ".intValue" and "+" on 100KB and 1000KB byte array.

#(unchecked-add-int (unchecked-multiply-int 31 %1) (hash-code %2))
1 alist))

(defn hash-code [obj]
(let [t (type obj)]
(if (contains? ARRAY-TYPES t)
(deep-hash-code obj)
(.hashCode obj))))

(defn list-hash-code [^List alist]
(.hashCode alist))
(deep-hash-code alist))