forked from hush/lightwalletd
Aditya Kulkarni
5 years ago
1 changed files with 65 additions and 0 deletions
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package common |
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import "github.com/pkg/errors" |
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type BlockCache struct { |
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MaxEntries int |
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FirstBlock int |
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LastBlock int |
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m map[int][]byte |
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} |
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func New(maxEntries int) *BlockCache { |
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return &BlockCache{ |
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MaxEntries: maxEntries, |
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FirstBlock: -1, |
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LastBlock: -1, |
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m: make(map[int][]byte), |
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} |
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} |
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func (c *BlockCache) Add(height int, bytes []byte) error { |
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if c.FirstBlock == -1 && c.LastBlock == -1 { |
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// If this is the first block, prep the data structure
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c.FirstBlock = height |
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c.LastBlock = height - 1 |
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} else if height >= c.FirstBlock && height <= c.LastBlock { |
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// Overwriting an existing entry. If so, then remove all
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// subsequent blocks, since this might be a reorg
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for i := height; i <= c.LastBlock; i++ { |
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delete(c.m, i) |
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} |
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} |
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if height != c.LastBlock+1 { |
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return errors.New("Blocks need to be added sequentially") |
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} |
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// Add the entry and update the counters
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c.m[height] = bytes |
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c.LastBlock = height |
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// If the cache is full, remove the oldest block
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if c.LastBlock-c.FirstBlock+1 > c.MaxEntries { |
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delete(c.m, c.FirstBlock) |
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c.FirstBlock = c.FirstBlock + 1 |
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} |
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return nil |
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} |
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func (c *BlockCache) Get(height int) ([]byte, error) { |
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if c.LastBlock == -1 || c.FirstBlock == -1 { |
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return nil, errors.New("Map is empty") |
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} |
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if height < c.FirstBlock || height > c.LastBlock { |
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return nil, errors.New("Index out of range") |
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} |
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return c.m[height], nil |
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} |
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