path: root/swarm/storage/memstore.go

// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// memory storage layer for the package blockhash

package storage

import (
    "context"

    lru "github.com/hashicorp/golang-lru"
)

type MemStore struct {
    cache    *lru.Cache
    disabled bool
}

//NewMemStore is instantiating a MemStore cache keeping all frequently requested
//chunks in the `cache` LRU cache.
func NewMemStore(params *StoreParams, _ *LDBStore) (m *MemStore) {
    if params.CacheCapacity == 0 {
        return &MemStore{
            disabled: true,
        }
    }

    c, err := lru.New(int(params.CacheCapacity))
    if err != nil {
        panic(err)
    }

    return &MemStore{
        cache: c,
    }
}

// Has needed to implement SyncChunkStore
func (m *MemStore) Has(_ context.Context, addr Address) bool {
    return m.cache.Contains(addr)
}

func (m *MemStore) Get(_ context.Context, addr Address) (Chunk, error) {
    if m.disabled {
        return nil, ErrChunkNotFound
    }

    c, ok := m.cache.Get(string(addr))
    if !ok {
        return nil, ErrChunkNotFound
    }
    return c.(Chunk), nil
}

func (m *MemStore) Put(_ context.Context, c Chunk) error {
    if m.disabled {
        return nil
    }

    m.cache.Add(string(c.Address()), c)
    return nil
}

func (m *MemStore) setCapacity(n int) {
    if n <= 0 {
        m.disabled = true
    } else {
        c, err := lru.New(n)
        if err != nil {
            panic(err)
        }

        *m = MemStore{
            cache: c,
        }
    }
}

func (s *MemStore) Close() {}