-
-
Notifications
You must be signed in to change notification settings - Fork 1.4k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
A `node256` is nearly 4KB in memory whereas a `node48` is closer to 1KB. Signed-off-by: Neil Twigg <neil@nats.io>
- Loading branch information
1 parent
3a32c41
commit d2bede5
Showing
5 changed files
with
220 additions
and
7 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,110 @@ | ||
| // Copyright 2023-2024 The NATS Authors | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package stree | ||
|
|
||
| // Node with 48 children | ||
| // Memory saving vs node256 comes from the fact that the child array is 16 bytes | ||
| // per `node` entry, so node256's 256*16=4096 vs node48's 256+(48*16)=1024 | ||
| // Note that `key` is effectively 1-indexed, as 0 means no entry, so offset by 1 | ||
| // Order of struct fields for best memory alignment (as per govet/fieldalignment) | ||
| type node48 struct { | ||
| key [256]byte | ||
| meta | ||
| child [48]node | ||
| } | ||
|
|
||
| func newNode48(prefix []byte) *node48 { | ||
| nn := &node48{} | ||
| nn.setPrefix(prefix) | ||
| return nn | ||
| } | ||
|
|
||
| func (n *node48) addChild(c byte, nn node) { | ||
| if n.size >= 48 { | ||
| panic("node48 full!") | ||
| } | ||
| n.child[n.size] = nn | ||
| n.key[c] = byte(n.size + 1) // 1-indexed | ||
| n.size++ | ||
| } | ||
|
|
||
| func (n *node48) findChild(c byte) *node { | ||
| i := n.key[c] | ||
| if i == 0 { | ||
| return nil | ||
| } | ||
| return &n.child[i-1] | ||
| } | ||
|
|
||
| func (n *node48) isFull() bool { return n.size >= 48 } | ||
|
|
||
| func (n *node48) grow() node { | ||
| nn := newNode256(n.prefix) | ||
| for c := byte(0); c < 255; c++ { | ||
| if i := n.key[c]; i > 0 { | ||
| nn.addChild(c, n.child[i-1]) | ||
| } | ||
| } | ||
| return nn | ||
| } | ||
|
|
||
| // Deletes a child from the node. | ||
| func (n *node48) deleteChild(c byte) { | ||
| i := n.key[c] | ||
| if i == 0 { | ||
| return | ||
| } | ||
| i-- // Adjust for 1-indexing | ||
| last := byte(n.size - 1) | ||
| if i < last { | ||
| n.child[i] = n.child[last] | ||
| for c := byte(0); c <= 255; c++ { | ||
| if n.key[c] == last+1 { | ||
| n.key[c] = i + 1 | ||
| break | ||
| } | ||
| } | ||
| } | ||
| n.child[last] = nil | ||
| n.key[c] = 0 | ||
| n.size-- | ||
| } | ||
|
|
||
| // Shrink if needed and return new node, otherwise return nil. | ||
| func (n *node48) shrink() node { | ||
| if n.size > 16 { | ||
| return nil | ||
| } | ||
| nn := newNode16(nil) | ||
| for c := byte(0); c < 255; c++ { | ||
| if i := n.key[c]; i > 0 { | ||
| nn.addChild(c, n.child[i-1]) | ||
| } | ||
| } | ||
| return nn | ||
| } | ||
|
|
||
| // Iterate over all children calling func f. | ||
| func (n *node48) iter(f func(node) bool) { | ||
| for _, c := range n.child { | ||
| if c != nil && !f(c) { | ||
| return | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // Return our children as a slice. | ||
| func (n *node48) children() []node { | ||
| return n.child[:n.size] | ||
| } |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters