// Capacity queries the underlying file system for disk capacity information.
func (r *RocksDB) Capacity() (roachpb.StoreCapacity, error) {
	fileSystemUsage := gosigar.FileSystemUsage{}
	dir := r.dir
	if dir == "" {
		dir = "/tmp"
	}
	if err := fileSystemUsage.Get(dir); err != nil {
		return roachpb.StoreCapacity{}, err
	}

	if fileSystemUsage.Total > math.MaxInt64 {
		return roachpb.StoreCapacity{}, fmt.Errorf("unsupported disk size %s, max supported size is %s",
			humanize.IBytes(fileSystemUsage.Total), humanizeutil.IBytes(math.MaxInt64))
	}
	if fileSystemUsage.Avail > math.MaxInt64 {
		return roachpb.StoreCapacity{}, fmt.Errorf("unsupported disk size %s, max supported size is %s",
			humanize.IBytes(fileSystemUsage.Avail), humanizeutil.IBytes(math.MaxInt64))
	}
	fsuTotal := int64(fileSystemUsage.Total)
	fsuAvail := int64(fileSystemUsage.Avail)

	// If no size limitation have been placed on the store size or if the
	// limitation is greater than what's available, just return the actual
	// totals.
	if r.maxSize == 0 || r.maxSize >= fsuTotal || r.dir == "" {
		return roachpb.StoreCapacity{
			Capacity:  fsuTotal,
			Available: fsuAvail,
		}, nil
	}

	// Find the total size of all the files in the r.dir and all its
	// subdirectories.
	var totalUsedBytes int64
	if errOuter := filepath.Walk(r.dir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return nil
		}
		if info.Mode().IsRegular() {
			totalUsedBytes += info.Size()
		}
		return nil
	}); errOuter != nil {
		return roachpb.StoreCapacity{}, errOuter
	}

	available := r.maxSize - totalUsedBytes
	if available > fsuAvail {
		available = fsuAvail
	}
	if available < 0 {
		available = 0
	}

	return roachpb.StoreCapacity{
		Capacity:  r.maxSize,
		Available: available,
	}, nil
}

// GetTotalMemory returns either the total system memory or if possible the
// cgroups available memory.
func GetTotalMemory() (int64, error) {
	mem := gosigar.Mem{}
	if err := mem.Get(); err != nil {
		return 0, err
	}
	if mem.Total > math.MaxInt64 {
		return 0, fmt.Errorf("inferred memory size %s exceeds maximum supported memory size %s",
			humanize.IBytes(mem.Total), humanize.Bytes(math.MaxInt64))
	}
	totalMem := int64(mem.Total)
	if runtime.GOOS == "linux" {
		var err error
		var buf []byte
		if buf, err = ioutil.ReadFile(defaultCGroupMemPath); err != nil {
			if log.V(1) {
				log.Infof(context.TODO(), "can't read available memory from cgroups (%s), using system memory %s instead", err,
					humanizeutil.IBytes(totalMem))
			}
			return totalMem, nil
		}
		var cgAvlMem uint64
		if cgAvlMem, err = strconv.ParseUint(strings.TrimSpace(string(buf)), 10, 64); err != nil {
			if log.V(1) {
				log.Infof(context.TODO(), "can't parse available memory from cgroups (%s), using system memory %s instead", err,
					humanizeutil.IBytes(totalMem))
			}
			return totalMem, nil
		}
		if cgAvlMem > math.MaxInt64 {
			if log.V(1) {
				log.Infof(context.TODO(), "available memory from cgroups is too large and unsupported %s using system memory %s instead",
					humanize.IBytes(cgAvlMem), humanizeutil.IBytes(totalMem))

			}
			return totalMem, nil
		}
		if cgAvlMem > mem.Total {
			if log.V(1) {
				log.Infof(context.TODO(), "available memory from cgroups %s exceeds system memory %s, using system memory",
					humanize.IBytes(cgAvlMem), humanizeutil.IBytes(totalMem))
			}
			return totalMem, nil
		}

		return int64(cgAvlMem), nil
	}
	return totalMem, nil
}

// String returns a fully parsable version of the store spec.
func (ss StoreSpec) String() string {
	var buffer bytes.Buffer
	if len(ss.Path) != 0 {
		fmt.Fprintf(&buffer, "path=%s,", ss.Path)
	}
	if ss.InMemory {
		fmt.Fprint(&buffer, "type=mem,")
	}
	if ss.SizeInBytes > 0 {
		fmt.Fprintf(&buffer, "size=%s,", humanizeutil.IBytes(ss.SizeInBytes))
	}
	if ss.SizePercent > 0 {
		fmt.Fprintf(&buffer, "size=%s%%,", humanize.Ftoa(ss.SizePercent))
	}
	if len(ss.Attributes.Attrs) > 0 {
		fmt.Fprint(&buffer, "attrs=")
		for i, attr := range ss.Attributes.Attrs {
			if i != 0 {
				fmt.Fprint(&buffer, ":")
			}
			fmt.Fprintf(&buffer, attr)
		}
		fmt.Fprintf(&buffer, ",")
	}
	// Trim the extra comma from the end if it exists.
	if l := buffer.Len(); l > 0 {
		buffer.Truncate(l - 1)
	}
	return buffer.String()
}

// Open creates options and opens the database. If the database
// doesn't yet exist at the specified directory, one is initialized
// from scratch. The RocksDB Open and Close methods are reference
// counted such that subsequent Open calls to an already opened
// RocksDB instance only bump the reference count. The RocksDB is only
// closed when a sufficient number of Close calls are performed to
// bring the reference count down to 0.
func (r *RocksDB) Open() error {
	if r.rdb != nil {
		return nil
	}

	if r.memtableBudget < minMemtableBudget {
		return util.Errorf("memtable budget must be at least %s: %s",
			humanize.IBytes(minMemtableBudget), humanizeutil.IBytes(r.memtableBudget))
	}

	var ver storageVersion
	if len(r.dir) != 0 {
		log.Infof("opening rocksdb instance at %q", r.dir)

		// Check the version number.
		var err error
		if ver, err = getVersion(r.dir); err != nil {
			return err
		}
		if ver < versionMinimum || ver > versionCurrent {
			// Instead of an error, we should call a migration if possible when
			// one is needed immediately following the DBOpen call.
			return fmt.Errorf("incompatible rocksdb data version, current:%d, on disk:%d, minimum:%d",
				versionCurrent, ver, versionMinimum)
		}
	} else {
		log.Infof("opening in memory rocksdb instance")

		// In memory dbs are always current.
		ver = versionCurrent
	}

	status := C.DBOpen(&r.rdb, goToCSlice([]byte(r.dir)),
		C.DBOptions{
			cache_size:      C.uint64_t(r.cacheSize),
			memtable_budget: C.uint64_t(r.memtableBudget),
			block_size:      C.uint64_t(envutil.EnvOrDefaultBytes("rocksdb_block_size", defaultBlockSize)),
			wal_ttl_seconds: C.uint64_t(envutil.EnvOrDefaultDuration("rocksdb_wal_ttl", 0).Seconds()),
			allow_os_buffer: C.bool(true),
			logging_enabled: C.bool(log.V(3)),
		})
	if err := statusToError(status); err != nil {
		return util.Errorf("could not open rocksdb instance: %s", err)
	}

	// Update or add the version file if needed.
	if ver < versionCurrent {
		if err := writeVersionFile(r.dir); err != nil {
			return err
		}
	}

	// Start a goroutine that will finish when the underlying handle
	// is deallocated. This is used to check a leak in tests.
	go func() {
		<-r.deallocated
	}()
	r.stopper.AddCloser(r)
	return nil
}

// InitStores initializes ctx.Engines based on ctx.Stores.
func (ctx *Context) InitStores(stopper *stop.Stopper) error {
	// TODO(peter): The comments and docs say that CacheSize and MemtableBudget
	// are split evenly if there are multiple stores, but we aren't doing that
	// currently. See #4979 and #4980.
	for _, spec := range ctx.Stores.Specs {
		var sizeInBytes = spec.SizeInBytes
		if spec.InMemory {
			if spec.SizePercent > 0 {
				sysMem, err := GetTotalMemory()
				if err != nil {
					return fmt.Errorf("could not retrieve system memory")
				}
				sizeInBytes = int64(float64(sysMem) * spec.SizePercent / 100)
			}
			if sizeInBytes != 0 && sizeInBytes < minimumStoreSize {
				return fmt.Errorf("%f%% of memory is only %s bytes, which is below the minimum requirement of %s",
					spec.SizePercent, humanizeutil.IBytes(sizeInBytes), humanizeutil.IBytes(minimumStoreSize))
			}
			ctx.Engines = append(ctx.Engines, engine.NewInMem(spec.Attributes, sizeInBytes, stopper))
		} else {
			if spec.SizePercent > 0 {
				fileSystemUsage := gosigar.FileSystemUsage{}
				if err := fileSystemUsage.Get(spec.Path); err != nil {
					return err
				}
				sizeInBytes = int64(float64(fileSystemUsage.Total) * spec.SizePercent / 100)
			}
			if sizeInBytes != 0 && sizeInBytes < minimumStoreSize {
				return fmt.Errorf("%f%% of %s's total free space is only %s bytes, which is below the minimum requirement of %s",
					spec.SizePercent, spec.Path, humanizeutil.IBytes(sizeInBytes), humanizeutil.IBytes(minimumStoreSize))
			}
			ctx.Engines = append(ctx.Engines, engine.NewRocksDB(spec.Attributes, spec.Path,
				ctx.CacheSize/int64(len(ctx.Stores.Specs)), ctx.MemtableBudget, sizeInBytes, stopper))
		}
	}
	if len(ctx.Engines) == 1 {
		log.Infof("1 storage engine initialized")
	} else {
		log.Infof("%d storage engines initialized", len(ctx.Engines))
	}
	return nil
}

// InitStores initializes ctx.Engines based on ctx.Stores.
func (ctx *Context) InitStores(stopper *stop.Stopper) error {
	cache := engine.NewRocksDBCache(ctx.CacheSize)
	defer cache.Release()

	for _, spec := range ctx.Stores.Specs {
		var sizeInBytes = spec.SizeInBytes
		if spec.InMemory {
			if spec.SizePercent > 0 {
				sysMem, err := GetTotalMemory()
				if err != nil {
					return fmt.Errorf("could not retrieve system memory")
				}
				sizeInBytes = int64(float64(sysMem) * spec.SizePercent / 100)
			}
			if sizeInBytes != 0 && sizeInBytes < minimumStoreSize {
				return fmt.Errorf("%f%% of memory is only %s bytes, which is below the minimum requirement of %s",
					spec.SizePercent, humanizeutil.IBytes(sizeInBytes), humanizeutil.IBytes(minimumStoreSize))
			}
			ctx.Engines = append(ctx.Engines, engine.NewInMem(spec.Attributes, sizeInBytes, stopper))
		} else {
			if spec.SizePercent > 0 {
				fileSystemUsage := gosigar.FileSystemUsage{}
				if err := fileSystemUsage.Get(spec.Path); err != nil {
					return err
				}
				sizeInBytes = int64(float64(fileSystemUsage.Total) * spec.SizePercent / 100)
			}
			if sizeInBytes != 0 && sizeInBytes < minimumStoreSize {
				return fmt.Errorf("%f%% of %s's total free space is only %s bytes, which is below the minimum requirement of %s",
					spec.SizePercent, spec.Path, humanizeutil.IBytes(sizeInBytes), humanizeutil.IBytes(minimumStoreSize))
			}
			ctx.Engines = append(ctx.Engines, engine.NewRocksDB(spec.Attributes, spec.Path,
				cache, ctx.MemtableBudget, sizeInBytes, stopper))
		}
	}
	if len(ctx.Engines) == 1 {
		log.Infof("1 storage engine initialized")
	} else {
		log.Infof("%d storage engines initialized", len(ctx.Engines))
	}
	return nil
}

func (b *bytesValue) String() string {
	// This uses the MiB, GiB, etc suffixes. If we use humanize.Bytes() we get
	// the MB, GB, etc suffixes, but the conversion is done in multiples of 1000
	// vs 1024.
	return humanizeutil.IBytes(*b.val)
}

// newStoreSpec parses the string passed into a --store flag and returns a
// StoreSpec if it is correctly parsed.
// There are four possible fields that can be passed in, comma separated:
// - path=xxx The directory in which to the rocks db instance should be
//   located, required unless using a in memory storage.
// - type=mem This specifies that the store is an in memory storage instead of
//   an on disk one. mem is currently the only other type available.
// - size=xxx The optional maximum size of the storage. This can be in one of a
//   few different formats.
//   - 10000000000     -> 10000000000 bytes
//   - 20GB            -> 20000000000 bytes
//   - 20GiB           -> 21474836480 bytes
//   - 0.02TiB         -> 21474836480 bytes
//   - 20%             -> 20% of the available space
//   - 0.2             -> 20% of the available space
// - attrs=xxx:yyy:zzz A colon separated list of optional attributes.
// Note that commas are forbidden within any field name or value.
func newStoreSpec(value string) (StoreSpec, error) {
	if len(value) == 0 {
		return StoreSpec{}, fmt.Errorf("no value specified")
	}
	var ss StoreSpec
	used := make(map[string]struct{})
	for _, split := range strings.Split(value, ",") {
		if len(split) == 0 {
			continue
		}
		subSplits := strings.SplitN(split, "=", 2)
		var field string
		var value string
		if len(subSplits) == 1 {
			field = "path"
			value = subSplits[0]
		} else {
			field = strings.ToLower(subSplits[0])
			value = subSplits[1]
		}
		if _, ok := used[field]; ok {
			return StoreSpec{}, fmt.Errorf("%s field was used twice in store definition", field)
		}
		used[field] = struct{}{}

		if len(field) == 0 {
			continue
		}
		if len(value) == 0 {
			return StoreSpec{}, fmt.Errorf("no value specified for %s", field)
		}

		switch field {
		case "path":
			if len(value) == 0 {

			}
			ss.Path = value
		case "size":
			if len(value) == 0 {
				return StoreSpec{}, fmt.Errorf("no size specified")
			}

			if unicode.IsDigit(rune(value[len(value)-1])) &&
				(strings.HasPrefix(value, "0.") || strings.HasPrefix(value, ".")) {
				// Value is a percentage without % sign.
				var err error
				ss.SizePercent, err = strconv.ParseFloat(value, 64)
				ss.SizePercent *= 100
				if err != nil {
					return StoreSpec{}, fmt.Errorf("could not parse store size (%s) %s", value, err)
				}
				if ss.SizePercent > 100 || ss.SizePercent < 1 {
					return StoreSpec{}, fmt.Errorf("store size (%s) must be between 1%% and 100%%", value)
				}
			} else if strings.HasSuffix(value, "%") {
				// Value is a percentage.
				var err error
				ss.SizePercent, err = strconv.ParseFloat(value[:len(value)-1], 64)
				if err != nil {
					return StoreSpec{}, fmt.Errorf("could not parse store size (%s) %s", value, err)
				}
				if ss.SizePercent > 100 || ss.SizePercent < 1 {
					return StoreSpec{}, fmt.Errorf("store size (%s) must be between 1%% and 100%%", value)
				}
			} else {
				var err error
				ss.SizeInBytes, err = humanizeutil.ParseBytes(value)
				if err != nil {
					return StoreSpec{}, fmt.Errorf("could not parse store size (%s) %s", value, err)
				}
				if ss.SizeInBytes < minimumStoreSize {
					return StoreSpec{}, fmt.Errorf("store size (%s) must be larger than %s", value,
						humanizeutil.IBytes(minimumStoreSize))
				}
			}
		case "attrs":
			if len(value) == 0 {
				return StoreSpec{}, fmt.Errorf("no attributes specified")
			}
			// Check to make sure there are no duplicate attributes.
			attrMap := make(map[string]struct{})
			for _, attribute := range strings.Split(value, ":") {
//.........这里部分代码省略.........

// Capacity queries the underlying file system for disk capacity information.
func (r *RocksDB) Capacity() (roachpb.StoreCapacity, error) {
	fileSystemUsage := gosigar.FileSystemUsage{}
	dir := r.dir
	if dir == "" {
		// This is an in-memory instance. Pretend we're empty since we
		// don't know better and only use this for testing. Using any
		// part of the actual file system here can throw off allocator
		// rebalancing in a hard-to-trace manner. See #7050.
		return roachpb.StoreCapacity{
			Capacity:  r.maxSize,
			Available: r.maxSize,
		}, nil
	}
	if err := fileSystemUsage.Get(dir); err != nil {
		return roachpb.StoreCapacity{}, err
	}

	if fileSystemUsage.Total > math.MaxInt64 {
		return roachpb.StoreCapacity{}, fmt.Errorf("unsupported disk size %s, max supported size is %s",
			humanize.IBytes(fileSystemUsage.Total), humanizeutil.IBytes(math.MaxInt64))
	}
	if fileSystemUsage.Avail > math.MaxInt64 {
		return roachpb.StoreCapacity{}, fmt.Errorf("unsupported disk size %s, max supported size is %s",
			humanize.IBytes(fileSystemUsage.Avail), humanizeutil.IBytes(math.MaxInt64))
	}
	fsuTotal := int64(fileSystemUsage.Total)
	fsuAvail := int64(fileSystemUsage.Avail)

	// If no size limitation have been placed on the store size or if the
	// limitation is greater than what's available, just return the actual
	// totals.
	if r.maxSize == 0 || r.maxSize >= fsuTotal || r.dir == "" {
		return roachpb.StoreCapacity{
			Capacity:  fsuTotal,
			Available: fsuAvail,
		}, nil
	}

	// Find the total size of all the files in the r.dir and all its
	// subdirectories.
	var totalUsedBytes int64
	if errOuter := filepath.Walk(r.dir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return nil
		}
		if info.Mode().IsRegular() {
			totalUsedBytes += info.Size()
		}
		return nil
	}); errOuter != nil {
		return roachpb.StoreCapacity{}, errOuter
	}

	available := r.maxSize - totalUsedBytes
	if available > fsuAvail {
		available = fsuAvail
	}
	if available < 0 {
		available = 0
	}

	return roachpb.StoreCapacity{
		Capacity:  r.maxSize,
		Available: available,
	}, nil
}

// TestHumanizeBytes verifies both IBytes and ParseBytes.
func TestBytes(t *testing.T) {
	defer leaktest.AfterTest(t)()

	testCases := []struct {
		value       int64
		exp         string
		expNeg      string
		parseExp    int64
		parseErr    string
		parseErrNeg string
	}{
		{0, "0 B", "0 B", 0, "", ""},
		{1024, "1.0 KiB", "-1.0 KiB", 1024, "", ""},
		{1024 << 10, "1.0 MiB", "-1.0 MiB", 1024 << 10, "", ""},
		{1024 << 20, "1.0 GiB", "-1.0 GiB", 1024 << 20, "", ""},
		{1024 << 30, "1.0 TiB", "-1.0 TiB", 1024 << 30, "", ""},
		{1024 << 40, "1.0 PiB", "-1.0 PiB", 1024 << 40, "", ""},
		{1024 << 50, "1.0 EiB", "-1.0 EiB", 1024 << 50, "", ""},
		{int64(math.MaxInt64), "8.0 EiB", "-8.0 EiB", 0, "too large: 8.0 EiB", "too large: -8.0 EiB"},
	}

	for i, testCase := range testCases {
		// Test IBytes.
		if actual := humanizeutil.IBytes(testCase.value); actual != testCase.exp {
			t.Errorf("%d: IBytes(%d) actual:%s does not match expected:%s", i, testCase.value, actual, testCase.exp)
		}
		// Test negative IBytes.
		if actual := humanizeutil.IBytes(-testCase.value); actual != testCase.expNeg {
			t.Errorf("%d: IBytes(%d) actual:%s does not match expected:%s", i, -testCase.value, actual,
				testCase.expNeg)
		}
		// Test ParseBytes.
		if actual, err := humanizeutil.ParseBytes(testCase.exp); err != nil {
			if len(testCase.parseErr) > 0 {
				if testCase.parseErr != err.Error() {
					t.Errorf("%d: ParseBytes(%s) caused an incorrect error actual:%s, expected:%s", i, testCase.exp,
						err, testCase.parseErr)
				}
			} else {
				t.Errorf("%d: ParseBytes(%s) caused an unexpected error:%s", i, testCase.exp, err)
			}
		} else if actual != testCase.parseExp {
			t.Errorf("%d: ParseBytes(%s) actual:%d does not match expected:%d", i, testCase.exp, actual,
				testCase.parseExp)
		}
		// Test negative ParseBytes.
		if actual, err := humanizeutil.ParseBytes(testCase.expNeg); err != nil {
			if len(testCase.parseErrNeg) > 0 {
				if testCase.parseErrNeg != err.Error() {
					t.Errorf("%d: ParseBytes(%s) caused an incorrect error actual:%s, expected:%s", i, testCase.expNeg,
						err, testCase.parseErrNeg)
				}
			} else {
				t.Errorf("%d: ParseBytes(%s) caused an unexpected error:%s", i, testCase.expNeg, err)
			}
		} else if actual != -testCase.parseExp {
			t.Errorf("%d: ParseBytes(%s) actual:%d does not match expected:%d", i, testCase.expNeg, actual,
				-testCase.parseExp)
		}
	}

	// Some extra error cases for good measure.
	testFailCases := []struct {
		value    string
		expected string
	}{
		{"", "parsing \"\": invalid syntax"},   // our error
		{"1 ZB", "unhandled size name: zb"},    // humanize's error
		{"-1 ZB", "unhandled size name: zb"},   // humanize's error
		{"1 ZiB", "unhandled size name: zib"},  // humanize's error
		{"-1 ZiB", "unhandled size name: zib"}, // humanize's error
		{"100 EiB", "too large: 100 EiB"},      // humanize's error
		{"-100 EiB", "too large: 100 EiB"},     // humanize's error
		{"10 EiB", "too large: 10 EiB"},        // our error
		{"-10 EiB", "too large: -10 EiB"},      // our error
	}
	for i, testCase := range testFailCases {
		if _, err := humanizeutil.ParseBytes(testCase.value); err.Error() != testCase.expected {
			t.Errorf("%d: ParseBytes(%s) caused an incorrect error actual:%s, expected:%s", i, testCase.value, err,
				testCase.expected)
		}
	}
}