all: clean up and proerly abstract database access

1 files changed, 418 insertions, 0 deletions

diff --git a/ethdb/leveldb/leveldb.go b/ethdb/leveldb/leveldb.go
new file mode 100644
index 000000000..11bba6b08
--- /dev/null
+++ b/ethdb/leveldb/leveldb.go
@@ -0,0 +1,418 @@
+// Copyright 2014 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/>.
+
+// +build !js
+
+// Package leveldb implements the key-value database layer based on LevelDB.
+package leveldb
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/metrics"
+	"github.com/syndtr/goleveldb/leveldb"
+	"github.com/syndtr/goleveldb/leveldb/errors"
+	"github.com/syndtr/goleveldb/leveldb/filter"
+	"github.com/syndtr/goleveldb/leveldb/opt"
+	"github.com/syndtr/goleveldb/leveldb/util"
+)
+
+const (
+	// leveldbDegradationWarnInterval specifies how often warning should be printed
+	// if the leveldb database cannot keep up with requested writes.
+	leveldbDegradationWarnInterval = time.Minute
+
+	// leveldbMinCache is the minimum amount of memory in megabytes to allocate to
+	// leveldb read and write caching, split half and half.
+	leveldbMinCache = 16
+
+	// leveldbMinHandles is the minimum number of files handles to allocate to the
+	// open database files.
+	leveldbMinHandles = 16
+
+	// metricsGatheringInterval specifies the interval to retrieve leveldb database
+	// compaction, io and pause stats to report to the user.
+	metricsGatheringInterval = 3 * time.Second
+)
+
+// LevelDBDatabase is a persistent key-value store. Apart from basic data storage
+// functionality it also supports batch writes and iterating over the keyspace in
+// binary-alphabetical order.
+type LevelDBDatabase struct {
+	fn string      // filename for reporting
+	db *leveldb.DB // LevelDB instance
+
+	compTimeMeter    metrics.Meter // Meter for measuring the total time spent in database compaction
+	compReadMeter    metrics.Meter // Meter for measuring the data read during compaction
+	compWriteMeter   metrics.Meter // Meter for measuring the data written during compaction
+	writeDelayNMeter metrics.Meter // Meter for measuring the write delay number due to database compaction
+	writeDelayMeter  metrics.Meter // Meter for measuring the write delay duration due to database compaction
+	diskReadMeter    metrics.Meter // Meter for measuring the effective amount of data read
+	diskWriteMeter   metrics.Meter // Meter for measuring the effective amount of data written
+
+	quitLock sync.Mutex      // Mutex protecting the quit channel access
+	quitChan chan chan error // Quit channel to stop the metrics collection before closing the database
+
+	log log.Logger // Contextual logger tracking the database path
+}
+
+// New returns a wrapped LevelDB object. The namespace is the prefix that the
+// metrics reporting should use for surfacing internal stats.
+func New(file string, cache int, handles int, namespace string) (*LevelDBDatabase, error) {
+	// Ensure we have some minimal caching and file guarantees
+	if cache < leveldbMinCache {
+		cache = leveldbMinCache
+	}
+	if handles < leveldbMinHandles {
+		handles = leveldbMinHandles
+	}
+	logger := log.New("database", file)
+	logger.Info("Allocated cache and file handles", "cache", common.StorageSize(cache*1024*1024), "handles", handles)
+
+	// Open the db and recover any potential corruptions
+	db, err := leveldb.OpenFile(file, &opt.Options{
+		OpenFilesCacheCapacity: handles,
+		BlockCacheCapacity:     cache / 2 * opt.MiB,
+		WriteBuffer:            cache / 4 * opt.MiB, // Two of these are used internally
+		Filter:                 filter.NewBloomFilter(10),
+	})
+	if _, corrupted := err.(*errors.ErrCorrupted); corrupted {
+		db, err = leveldb.RecoverFile(file, nil)
+	}
+	if err != nil {
+		return nil, err
+	}
+	// Assemble the wrapper with all the registered metrics
+	ldb := &LevelDBDatabase{
+		fn:       file,
+		db:       db,
+		log:      logger,
+		quitChan: make(chan chan error),
+	}
+	ldb.compTimeMeter = metrics.NewRegisteredMeter(namespace+"compact/time", nil)
+	ldb.compReadMeter = metrics.NewRegisteredMeter(namespace+"compact/input", nil)
+	ldb.compWriteMeter = metrics.NewRegisteredMeter(namespace+"compact/output", nil)
+	ldb.diskReadMeter = metrics.NewRegisteredMeter(namespace+"disk/read", nil)
+	ldb.diskWriteMeter = metrics.NewRegisteredMeter(namespace+"disk/write", nil)
+	ldb.writeDelayMeter = metrics.NewRegisteredMeter(namespace+"compact/writedelay/duration", nil)
+	ldb.writeDelayNMeter = metrics.NewRegisteredMeter(namespace+"compact/writedelay/counter", nil)
+
+	// Start up the metrics gathering and return
+	go ldb.meter(metricsGatheringInterval)
+	return ldb, nil
+}
+
+// Close stops the metrics collection, flushes any pending data to disk and closes
+// all io accesses to the underlying key-value store.
+func (db *LevelDBDatabase) Close() error {
+	db.quitLock.Lock()
+	defer db.quitLock.Unlock()
+
+	if db.quitChan != nil {
+		errc := make(chan error)
+		db.quitChan <- errc
+		if err := <-errc; err != nil {
+			db.log.Error("Metrics collection failed", "err", err)
+		}
+		db.quitChan = nil
+	}
+	return db.db.Close()
+}
+
+// Has retrieves if a key is present in the key-value store.
+func (db *LevelDBDatabase) Has(key []byte) (bool, error) {
+	return db.db.Has(key, nil)
+}
+
+// Get retrieves the given key if it's present in the key-value store.
+func (db *LevelDBDatabase) Get(key []byte) ([]byte, error) {
+	dat, err := db.db.Get(key, nil)
+	if err != nil {
+		return nil, err
+	}
+	return dat, nil
+}
+
+// Put inserts the given value into the key-value store.
+func (db *LevelDBDatabase) Put(key []byte, value []byte) error {
+	return db.db.Put(key, value, nil)
+}
+
+// Delete removes the key from the key-value store.
+func (db *LevelDBDatabase) Delete(key []byte) error {
+	return db.db.Delete(key, nil)
+}
+
+// NewBatch creates a write-only key-value store that buffers changes to its host
+// database until a final write is called.
+func (db *LevelDBDatabase) NewBatch() ethdb.Batch {
+	return &levelDBBatch{
+		db: db.db,
+		b:  new(leveldb.Batch),
+	}
+}
+
+// NewIterator creates a binary-alphabetical iterator over the entire keyspace
+// contained within the leveldb database.
+func (db *LevelDBDatabase) NewIterator() ethdb.Iterator {
+	return db.NewIteratorWithPrefix(nil)
+}
+
+// NewIteratorWithPrefix creates a binary-alphabetical iterator over a subset
+// of database content with a particular key prefix.
+func (db *LevelDBDatabase) NewIteratorWithPrefix(prefix []byte) ethdb.Iterator {
+	return db.db.NewIterator(util.BytesPrefix(prefix), nil)
+}
+
+// Stat returns a particular internal stat of the database.
+func (db *LevelDBDatabase) Stat(property string) (string, error) {
+	return db.db.GetProperty(property)
+}
+
+// Compact flattens the underlying data store for the given key range. In essence,
+// deleted and overwritten versions are discarded, and the data is rearranged to
+// reduce the cost of operations needed to access them.
+//
+// A nil start is treated as a key before all keys in the data store; a nil limit
+// is treated as a key after all keys in the data store. If both is nil then it
+// will compact entire data store.
+func (db *LevelDBDatabase) Compact(start []byte, limit []byte) error {
+	return db.db.CompactRange(util.Range{Start: start, Limit: limit})
+}
+
+// Path returns the path to the database directory.
+func (db *LevelDBDatabase) Path() string {
+	return db.fn
+}
+
+// meter periodically retrieves internal leveldb counters and reports them to
+// the metrics subsystem.
+//
+// This is how a LevelDB stats table looks like (currently):
+//   Compactions
+//    Level |   Tables   |    Size(MB)   |    Time(sec)  |    Read(MB)   |   Write(MB)
+//   -------+------------+---------------+---------------+---------------+---------------
+//      0   |          0 |       0.00000 |       1.27969 |       0.00000 |      12.31098
+//      1   |         85 |     109.27913 |      28.09293 |     213.92493 |     214.26294
+//      2   |        523 |    1000.37159 |       7.26059 |      66.86342 |      66.77884
+//      3   |        570 |    1113.18458 |       0.00000 |       0.00000 |       0.00000
+//
+// This is how the write delay look like (currently):
+// DelayN:5 Delay:406.604657ms Paused: false
+//
+// This is how the iostats look like (currently):
+// Read(MB):3895.04860 Write(MB):3654.64712
+func (db *LevelDBDatabase) meter(refresh time.Duration) {
+	// Create the counters to store current and previous compaction values
+	compactions := make([][]float64, 2)
+	for i := 0; i < 2; i++ {
+		compactions[i] = make([]float64, 3)
+	}
+	// Create storage for iostats.
+	var iostats [2]float64
+
+	// Create storage and warning log tracer for write delay.
+	var (
+		delaystats      [2]int64
+		lastWritePaused time.Time
+	)
+
+	var (
+		errc chan error
+		merr error
+	)
+
+	// Iterate ad infinitum and collect the stats
+	for i := 1; errc == nil && merr == nil; i++ {
+		// Retrieve the database stats
+		stats, err := db.db.GetProperty("leveldb.stats")
+		if err != nil {
+			db.log.Error("Failed to read database stats", "err", err)
+			merr = err
+			continue
+		}
+		// Find the compaction table, skip the header
+		lines := strings.Split(stats, "\n")
+		for len(lines) > 0 && strings.TrimSpace(lines[0]) != "Compactions" {
+			lines = lines[1:]
+		}
+		if len(lines) <= 3 {
+			db.log.Error("Compaction leveldbTable not found")
+			merr = errors.New("compaction leveldbTable not found")
+			continue
+		}
+		lines = lines[3:]
+
+		// Iterate over all the leveldbTable rows, and accumulate the entries
+		for j := 0; j < len(compactions[i%2]); j++ {
+			compactions[i%2][j] = 0
+		}
+		for _, line := range lines {
+			parts := strings.Split(line, "|")
+			if len(parts) != 6 {
+				break
+			}
+			for idx, counter := range parts[3:] {
+				value, err := strconv.ParseFloat(strings.TrimSpace(counter), 64)
+				if err != nil {
+					db.log.Error("Compaction entry parsing failed", "err", err)
+					merr = err
+					continue
+				}
+				compactions[i%2][idx] += value
+			}
+		}
+		// Update all the requested meters
+		if db.compTimeMeter != nil {
+			db.compTimeMeter.Mark(int64((compactions[i%2][0] - compactions[(i-1)%2][0]) * 1000 * 1000 * 1000))
+		}
+		if db.compReadMeter != nil {
+			db.compReadMeter.Mark(int64((compactions[i%2][1] - compactions[(i-1)%2][1]) * 1024 * 1024))
+		}
+		if db.compWriteMeter != nil {
+			db.compWriteMeter.Mark(int64((compactions[i%2][2] - compactions[(i-1)%2][2]) * 1024 * 1024))
+		}
+
+		// Retrieve the write delay statistic
+		writedelay, err := db.db.GetProperty("leveldb.writedelay")
+		if err != nil {
+			db.log.Error("Failed to read database write delay statistic", "err", err)
+			merr = err
+			continue
+		}
+		var (
+			delayN        int64
+			delayDuration string
+			duration      time.Duration
+			paused        bool
+		)
+		if n, err := fmt.Sscanf(writedelay, "DelayN:%d Delay:%s Paused:%t", &delayN, &delayDuration, &paused); n != 3 || err != nil {
+			db.log.Error("Write delay statistic not found")
+			merr = err
+			continue
+		}
+		duration, err = time.ParseDuration(delayDuration)
+		if err != nil {
+			db.log.Error("Failed to parse delay duration", "err", err)
+			merr = err
+			continue
+		}
+		if db.writeDelayNMeter != nil {
+			db.writeDelayNMeter.Mark(delayN - delaystats[0])
+		}
+		if db.writeDelayMeter != nil {
+			db.writeDelayMeter.Mark(duration.Nanoseconds() - delaystats[1])
+		}
+		// If a warning that db is performing compaction has been displayed, any subsequent
+		// warnings will be withheld for one minute not to overwhelm the user.
+		if paused && delayN-delaystats[0] == 0 && duration.Nanoseconds()-delaystats[1] == 0 &&
+			time.Now().After(lastWritePaused.Add(leveldbDegradationWarnInterval)) {
+			db.log.Warn("Database compacting, degraded performance")
+			lastWritePaused = time.Now()
+		}
+		delaystats[0], delaystats[1] = delayN, duration.Nanoseconds()
+
+		// Retrieve the database iostats.
+		ioStats, err := db.db.GetProperty("leveldb.iostats")
+		if err != nil {
+			db.log.Error("Failed to read database iostats", "err", err)
+			merr = err
+			continue
+		}
+		var nRead, nWrite float64
+		parts := strings.Split(ioStats, " ")
+		if len(parts) < 2 {
+			db.log.Error("Bad syntax of ioStats", "ioStats", ioStats)
+			merr = fmt.Errorf("bad syntax of ioStats %s", ioStats)
+			continue
+		}
+		if n, err := fmt.Sscanf(parts[0], "Read(MB):%f", &nRead); n != 1 || err != nil {
+			db.log.Error("Bad syntax of read entry", "entry", parts[0])
+			merr = err
+			continue
+		}
+		if n, err := fmt.Sscanf(parts[1], "Write(MB):%f", &nWrite); n != 1 || err != nil {
+			db.log.Error("Bad syntax of write entry", "entry", parts[1])
+			merr = err
+			continue
+		}
+		if db.diskReadMeter != nil {
+			db.diskReadMeter.Mark(int64((nRead - iostats[0]) * 1024 * 1024))
+		}
+		if db.diskWriteMeter != nil {
+			db.diskWriteMeter.Mark(int64((nWrite - iostats[1]) * 1024 * 1024))
+		}
+		iostats[0], iostats[1] = nRead, nWrite
+
+		// Sleep a bit, then repeat the stats collection
+		select {
+		case errc = <-db.quitChan:
+			// Quit requesting, stop hammering the database
+		case <-time.After(refresh):
+			// Timeout, gather a new set of stats
+		}
+	}
+
+	if errc == nil {
+		errc = <-db.quitChan
+	}
+	errc <- merr
+}
+
+// levelDBBatch is a write-only leveldb batch that commits changes to its host
+// database when Write is called. A batch cannot be used concurrently.
+type levelDBBatch struct {
+	db   *leveldb.DB
+	b    *leveldb.Batch
+	size int
+}
+
+// Put inserts the given value into the batch for later committing.
+func (b *levelDBBatch) Put(key, value []byte) error {
+	b.b.Put(key, value)
+	b.size += len(value)
+	return nil
+}
+
+// Delete inserts the a key removal into the batch for later committing.
+func (b *levelDBBatch) Delete(key []byte) error {
+	b.b.Delete(key)
+	b.size += 1
+	return nil
+}
+
+// ValueSize retrieves the amount of data queued up for writing.
+func (b *levelDBBatch) ValueSize() int {
+	return b.size
+}
+
+// Write flushes any accumulated data to disk.
+func (b *levelDBBatch) Write() error {
+	return b.db.Write(b.b, nil)
+}
+
+// Reset resets the batch for reuse.
+func (b *levelDBBatch) Reset() {
+	b.b.Reset()
+	b.size = 0
+}