wip wrap boltdb to get path information

finished but doesn't handle deleting deeply nested buckets

client/state/kvcodec.go

@@ -12,38 +12,36 @@ import (
 )
 
 type kvStore interface {
+	Path() []byte
+	Bucket(name []byte) kvStore
+	CreateBucket(key []byte) (kvStore, error)
+	CreateBucketIfNotExists(key []byte) (kvStore, error)
+	DeleteBucket(key []byte) error
 	Get(key []byte) (val []byte)
 	Put(key, val []byte) error
-	Writable() bool
 }
 
 // keyValueCodec handles encoding and decoding values from a key/value store
 // such as boltdb.
 type keyValueCodec struct {
-	// hashes maps keys to the hash of the last content written
-	hashes     map[string][]byte
+	// hashes maps buckets to keys to the hash of the last content written:
+	//   bucket -> key -> hash  for example:
+	//   allocations/1234       -> alloc      -> abcd
+	//   allocations/1234/redis -> task_state -> efff
+	hashes     map[string]map[string][]byte
 	hashesLock sync.Mutex
 }
 
 func newKeyValueCodec() *keyValueCodec {
 	return &keyValueCodec{
-		hashes: make(map[string][]byte),
+		hashes: make(map[string]map[string][]byte),
 	}
 }
 
-// hashKey returns a unique key for each hashed boltdb value
-func (c *keyValueCodec) hashKey(path string, key []byte) string {
-	return path + "-" + string(key)
-}
-
 // Put into kv store iff it has changed since the last write. A globally
 // unique key is constructed for each value by concatinating the path and key
 // passed in.
-func (c *keyValueCodec) Put(bkt kvStore, path string, key []byte, val interface{}) error {
-	if !bkt.Writable() {
-		return fmt.Errorf("bucket must be writable")
-	}
-
+func (c *keyValueCodec) Put(bkt kvStore, key []byte, val interface{}) error {
 	// buffer for writing serialized state to
 	var buf bytes.Buffer
 
@@ -63,24 +61,34 @@ func (c *keyValueCodec) Put(bkt kvStore, path string, key []byte, val interface{
 	}
 
 	// If the hashes are equal, skip the write
+	hashPath := string(bkt.Path())
+	hashKey := string(key)
 	hashVal := h.Sum(nil)
-	hashKey := c.hashKey(path, key)
+
+	// lastHash value or nil if it hasn't been hashed yet
+	var lastHash []byte
 
 	c.hashesLock.Lock()
-	persistedHash := c.hashes[hashKey]
+	if hashBkt, ok := c.hashes[hashPath]; ok {
+		lastHash = hashBkt[hashKey]
+	} else {
+		// Create hash bucket
+		c.hashes[hashPath] = make(map[string][]byte, 2)
+	}
 	c.hashesLock.Unlock()
 
-	if bytes.Equal(hashVal, persistedHash) {
+	if bytes.Equal(hashVal, lastHash) {
 		return nil
 	}
 
+	// New value: write it to the underlying store
 	if err := bkt.Put(key, buf.Bytes()); err != nil {
 		return fmt.Errorf("failed to write data at key %s: %v", key, err)
 	}
 
-	// New value written, store hash
+	// New value written, store hash (bucket path map was created above)
 	c.hashesLock.Lock()
-	c.hashes[hashKey] = hashVal
+	c.hashes[hashPath][hashKey] = hashVal
 	c.hashesLock.Unlock()
 
 	return nil
@@ -102,3 +110,23 @@ func (c *keyValueCodec) Get(bkt kvStore, key []byte, obj interface{}) error {
 
 	return nil
 }
+
+// DeleteBucket or do nothing if bucket doesn't exist.
+func (c *keyValueCodec) DeleteBucket(parent kvStore, bktName []byte) error {
+	// Get the path of the bucket being deleted
+	bkt := parent.Bucket(bktName)
+	if bkt == nil {
+		// Doesn't exist! Nothing to delete
+		return nil
+	}
+
+	// Delete the bucket
+	err := parent.DeleteBucket(bktName)
+
+	// Always purge all corresponding hashes to prevent memory leaks
+	c.hashesLock.Lock()
+	delete(c.hashes, string(bkt.Path()))
+	c.hashesLock.Unlock()
+
+	return err
+}

client/state/kvcodec_test.go

@@ -12,6 +12,26 @@ type mockKVStore struct {
 	puts int
 }
 
+func (mockKVStore) Path() []byte {
+	return []byte{}
+}
+
+func (m *mockKVStore) Bucket(name []byte) kvStore {
+	return m
+}
+
+func (m *mockKVStore) CreateBucket(key []byte) (kvStore, error) {
+	return m, nil
+}
+
+func (m *mockKVStore) CreateBucketIfNotExists(key []byte) (kvStore, error) {
+	return m, nil
+}
+
+func (m *mockKVStore) DeleteBucket(key []byte) error {
+	return nil
+}
+
 func (mockKVStore) Get(key []byte) (val []byte) {
 	return nil
 }
@@ -21,10 +41,6 @@ func (m *mockKVStore) Put(key, val []byte) error {
 	return nil
 }
 
-func (mockKVStore) Writable() bool {
-	return true
-}
-
 // TestKVCodec_PutHash asserts that Puts on the underlying kvstore only occur
 // when the data actually changes.
 func TestKVCodec_PutHash(t *testing.T) {
@@ -33,7 +49,6 @@ func TestKVCodec_PutHash(t *testing.T) {
 
 	// Create arguments for Put
 	kv := new(mockKVStore)
-	path := "path-path"
 	key := []byte("key1")
 	val := &struct {
 		Val int
@@ -42,29 +57,24 @@ func TestKVCodec_PutHash(t *testing.T) {
 	}
 
 	// Initial Put should be written
-	require.NoError(codec.Put(kv, path, key, val))
+	require.NoError(codec.Put(kv, key, val))
 	require.Equal(1, kv.puts)
 
 	// Writing the same values again should be a noop
-	require.NoError(codec.Put(kv, path, key, val))
+	require.NoError(codec.Put(kv, key, val))
 	require.Equal(1, kv.puts)
 
 	// Changing the value should write again
 	val.Val++
-	require.NoError(codec.Put(kv, path, key, val))
+	require.NoError(codec.Put(kv, key, val))
 	require.Equal(2, kv.puts)
 
 	// Changing the key should write again
 	key = []byte("key2")
-	require.NoError(codec.Put(kv, path, key, val))
+	require.NoError(codec.Put(kv, key, val))
 	require.Equal(3, kv.puts)
 
-	// Changing the path should write again
-	path = "new-path"
-	require.NoError(codec.Put(kv, path, key, val))
-	require.Equal(4, kv.puts)
-
 	// Writing the same values again should be a noop
-	require.NoError(codec.Put(kv, path, key, val))
-	require.Equal(4, kv.puts)
+	require.NoError(codec.Put(kv, key, val))
+	require.Equal(3, kv.puts)
 }

client/state/named_bucket.go

+package state
+
+import "github.com/boltdb/bolt"
+
+// namedBucket is a wrapper around bolt.Bucket's to preserve their path
+// information and expose it via the Path() method.
+//
+// Knowing the full bucket path to a key is necessary for tracking accesses in
+// another datastructure such as the hashing writer keyValueCodec.
+type namedBucket struct {
+	path []byte
+	name []byte
+	bkt  *bolt.Bucket
+}
+
+// newNamedBucket from a bolt transaction.
+func newNamedBucket(tx *bolt.Tx, root []byte) *namedBucket {
+	b := tx.Bucket(root)
+	if b == nil {
+		return nil
+	}
+
+	return &namedBucket{
+		path: root,
+		name: root,
+		bkt:  b,
+	}
+}
+
+// createNamedBucketIfNotExists from a bolt transaction.
+func createNamedBucketIfNotExists(tx *bolt.Tx, root []byte) (*namedBucket, error) {
+	b, err := tx.CreateBucketIfNotExists(root)
+	if err != nil {
+		return nil, err
+	}
+
+	return &namedBucket{
+		path: root,
+		name: root,
+		bkt:  b,
+	}, nil
+}
+
+// Path to this bucket (including this bucket).
+func (n *namedBucket) Path() []byte {
+	return n.path
+}
+
+// Name of this bucket.
+func (n *namedBucket) Name() []byte {
+	return n.name
+}
+
+// Bucket returns a bucket inside the current one or nil if the bucket does not
+// exist.
+func (n *namedBucket) Bucket(name []byte) kvStore {
+	b := n.bkt.Bucket(name)
+	if b == nil {
+		return nil
+	}
+
+	return &namedBucket{
+		path: n.chBkt(name),
+		name: name,
+		bkt:  b,
+	}
+}
+
+// CreateBucketIfNotExists creates a bucket if it doesn't exist and returns it
+// or an error.
+func (n *namedBucket) CreateBucketIfNotExists(name []byte) (kvStore, error) {
+	b, err := n.bkt.CreateBucketIfNotExists(name)
+	if err != nil {
+		return nil, err
+	}
+
+	return &namedBucket{
+		path: n.chBkt(name),
+		name: name,
+		bkt:  b,
+	}, nil
+}
+
+// CreateBucket creates a bucket and returns it.
+func (n *namedBucket) CreateBucket(name []byte) (kvStore, error) {
+	b, err := n.bkt.CreateBucket(name)
+	if err != nil {
+		return nil, err
+	}
+
+	return &namedBucket{
+		path: n.chBkt(name),
+		name: name,
+		bkt:  b,
+	}, nil
+}
+
+// DeleteBucket calls DeleteBucket on the underlying bolt.Bucket.
+func (n *namedBucket) DeleteBucket(name []byte) error {
+	return n.bkt.DeleteBucket(name)
+}
+
+// Get calls Get on the underlying bolt.Bucket.
+func (n *namedBucket) Get(key []byte) []byte {
+	return n.bkt.Get(key)
+}
+
+// Put calls Put on the underlying bolt.Bucket.
+func (n *namedBucket) Put(key, value []byte) error {
+	return n.bkt.Put(key, value)
+}
+
+// chBkt is like chdir but for buckets: it appends the new name to the end of
+// a copy of the path and returns it.
+func (n *namedBucket) chBkt(name []byte) []byte {
+	// existing path + new path element + path separator
+	path := make([]byte, len(n.path)+len(name)+1)
+	copy(path[0:len(n.path)], n.path)
+	path[len(n.path)] = '/'
+	copy(path[len(n.path)+1:], name)
+
+	return path
+}

client/state/named_bucket_test.go

+package state
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/boltdb/bolt"
+	"github.com/stretchr/testify/require"
+)
+
+func setupBoltDB(t *testing.T) (*bolt.DB, func()) {
+	dir, err := ioutil.TempDir("", "nomadtest_")
+	require.NoError(t, err)
+	cleanup := func() {
+		if err := os.RemoveAll(dir); err != nil {
+			t.Logf("error removing test dir: %v", err)
+		}
+	}
+
+	dbFilename := filepath.Join(dir, "nomadtest.db")
+	db, err := bolt.Open(dbFilename, 0600, nil)
+	if err != nil {
+		cleanup()
+		t.Fatalf("error creating boltdb: %v", err)
+	}
+
+	return db, func() {
+		db.Close()
+		cleanup()
+	}
+}
+
+// TestNamedBucket_Path asserts that creating and changing buckets are tracked
+// properly by the namedBucket wrapper.
+func TestNamedBucket_Path(t *testing.T) {
+	t.Parallel()
+	require := require.New(t)
+
+	db, cleanup := setupBoltDB(t)
+	defer cleanup()
+
+	parentBktName, childBktName := []byte("root"), []byte("child")
+	parentKey, parentVal := []byte("pkey"), []byte("pval")
+	childKey, childVal := []byte("ckey"), []byte("cval")
+
+	require.NoError(db.Update(func(tx *bolt.Tx) error {
+		// Trying to open a named bucket from a nonexistent bucket
+		// should return nil.
+		require.Nil(newNamedBucket(tx, []byte("nonexistent")))
+
+		// Creating a named bucket from a bolt tx should work and set
+		// the path and name properly.
+		b, err := createNamedBucketIfNotExists(tx, parentBktName)
+		require.NoError(err)
+		require.Equal(parentBktName, b.Name())
+		require.Equal(parentBktName, b.Path())
+
+		// Trying to descend into a nonexistent bucket should return
+		// nil.
+		require.Nil(b.Bucket([]byte("nonexistent")))
+
+		// Descending into a new bucket should update the path.
+		childBkt, err := b.CreateBucket(childBktName)
+		require.NoError(err)
+		require.Equal(childBktName, childBkt.(*namedBucket).Name())
+		require.Equal([]byte("root/child"), childBkt.Path())
+
+		// Assert the parent bucket did not get changed.
+		require.Equal(parentBktName, b.Name())
+		require.Equal(parentBktName, b.Path())
+
+		// Add entries to both buckets
+		require.NoError(b.Put(parentKey, parentVal))
+		require.NoError(childBkt.Put(childKey, childVal))
+		return nil
+	}))
+
+	// Read buckets and values back out
+	require.NoError(db.View(func(tx *bolt.Tx) error {
+		b := newNamedBucket(tx, parentBktName)
+		require.NotNil(b)
+		require.Equal(parentVal, b.Get(parentKey))
+		require.Nil(b.Get(childKey))
+
+		childBkt := b.Bucket(childBktName)
+		require.NotNil(childBkt)
+		require.Nil(childBkt.Get(parentKey))
+		require.Equal(childVal, childBkt.Get(childKey))
+		return nil
+	}))
+}
+
+// TestNamedBucket_DeleteBucket asserts that deleting a bucket properly purges
+// all related keys from the internal hashes map.
+func TestNamedBucket_DeleteBucket(t *testing.T) {
+	t.Parallel()
+	require := require.New(t)
+
+	db, cleanup := setupBoltDB(t)
+	defer cleanup()
+
+	// Create some nested buckets and keys (key values will just be their names)
+	b1Name, c1Name, c2Name, c1c1Name := []byte("b1"), []byte("c1"), []byte("c2"), []byte("c1c1")
+	b1k1, c1k1, c2k1, c1c1k1 := []byte("b1k1"), []byte("c1k1"), []byte("c2k1"), []byte("c1c1k1")
+
+	codec := newKeyValueCodec()
+
+	// Create initial db state
+	require.NoError(db.Update(func(tx *bolt.Tx) error {
+		// Create bucket 1 and key
+		b1, err := createNamedBucketIfNotExists(tx, b1Name)
+		require.NoError(err)
+		require.NoError(codec.Put(b1, b1k1, b1k1))
+
+		// Create child bucket 1 and key
+		c1, err := b1.CreateBucketIfNotExists(c1Name)
+		require.NoError(err)
+		require.NoError(codec.Put(c1, c1k1, c1k1))
+
+		// Create child-child bucket 1 and key
+		c1c1, err := c1.CreateBucketIfNotExists(c1c1Name)
+		require.NoError(err)
+		require.NoError(codec.Put(c1c1, c1c1k1, c1c1k1))
+
+		// Create child bucket 2 and key
+		c2, err := b1.CreateBucketIfNotExists(c2Name)
+		require.NoError(err)
+		require.NoError(codec.Put(c2, c2k1, c2k1))
+		return nil
+	}))
+
+	// codec should be tracking 4 hash buckets (b1, c1, c2, c1c1)
+	require.Len(codec.hashes, 4)
+
+	// Delete c1
+	require.NoError(db.Update(func(tx *bolt.Tx) error {
+		b1 := newNamedBucket(tx, b1Name)
+		return codec.DeleteBucket(b1, c1Name)
+	}))
+
+	START HERE // We don't appear to be properly deleting the sub-bucket
+	// codec should be tracking 2 hash buckets (b1, c2)
+	require.Len(codec.hashes, 2)
+
+	// Assert all of c1 is gone
+	require.NoError(db.View(func(tx *bolt.Tx) error {
+		return nil
+	}))
+}

client/state/state_database.go

@@ -3,7 +3,6 @@ package state
 import (
 	"fmt"
 	"path/filepath"
-	"strings"
 
 	"github.com/boltdb/bolt"
 	trstate "github.com/hashicorp/nomad/client/allocrunnerv2/taskrunner/state"
@@ -39,56 +38,6 @@ var (
 	taskStateKey      = []byte("task_state")
 )
 
-//TODO delete from kvcodec
-// DeleteAllocationBucket is used to delete an allocation bucket if it exists.
-func DeleteAllocationBucket(tx *bolt.Tx, allocID string) error {
-	if !tx.Writable() {
-		return fmt.Errorf("transaction must be writable")
-	}
-
-	// Retrieve the root allocations bucket
-	allocations := tx.Bucket(allocationsBucket)
-	if allocations == nil {
-		return nil
-	}
-
-	// Check if the bucket exists
-	key := []byte(allocID)
-	if allocBkt := allocations.Bucket(key); allocBkt == nil {
-		return nil
-	}
-
-	return allocations.DeleteBucket(key)
-}
-
-//TODO delete from kvcodec
-// DeleteTaskBucket is used to delete a task bucket if it exists.
-func DeleteTaskBucket(tx *bolt.Tx, allocID, taskName string) error {
-	if !tx.Writable() {
-		return fmt.Errorf("transaction must be writable")
-	}
-
-	// Retrieve the root allocations bucket
-	allocations := tx.Bucket(allocationsBucket)
-	if allocations == nil {
-		return nil
-	}
-
-	// Retrieve the specific allocations bucket
-	alloc := allocations.Bucket([]byte(allocID))
-	if alloc == nil {
-		return nil
-	}
-
-	// Check if the bucket exists
-	key := []byte(taskName)
-	if taskBkt := alloc.Bucket(key); taskBkt == nil {
-		return nil
-	}
-
-	return alloc.DeleteBucket(key)
-}
-
 // NewStateDBFunc creates a StateDB given a state directory.
 type NewStateDBFunc func(stateDir string) (StateDB, error)
 
@@ -153,7 +102,7 @@ type allocEntry struct {
 }
 
 func (s *BoltStateDB) getAllAllocations(tx *bolt.Tx) ([]*structs.Allocation, map[string]error) {
-	allocationsBkt := tx.Bucket(allocationsBucket)
+	allocationsBkt := newNamedBucket(tx, allocationsBucket)
 	if allocationsBkt == nil {
 		// No allocs
 		return nil, nil
@@ -163,7 +112,7 @@ func (s *BoltStateDB) getAllAllocations(tx *bolt.Tx) ([]*structs.Allocation, map
 	errs := map[string]error{}
 
 	// Create a cursor for iteration.
-	c := allocationsBkt.Cursor()
+	c := allocationsBkt.bkt.Cursor()
 
 	// Iterate over all the allocation buckets
 	for k, _ := c.First(); k != nil; k, _ = c.Next() {
@@ -190,7 +139,7 @@ func (s *BoltStateDB) getAllAllocations(tx *bolt.Tx) ([]*structs.Allocation, map
 func (s *BoltStateDB) PutAllocation(alloc *structs.Allocation) error {
 	return s.db.Update(func(tx *bolt.Tx) error {
 		// Retrieve the root allocations bucket
-		allocsBkt, err := tx.CreateBucketIfNotExists(allocationsBucket)
+		allocsBkt, err := createNamedBucketIfNotExists(tx, allocationsBucket)
 		if err != nil {
 			return err
 		}
@@ -205,7 +154,7 @@ func (s *BoltStateDB) PutAllocation(alloc *structs.Allocation) error {
 		allocState := allocEntry{
 			Alloc: alloc,
 		}
-		return s.codec.Put(allocBkt, alloc.ID, allocKey, &allocState)
+		return s.codec.Put(allocBkt, allocKey, &allocState)
 	})
 }
 
@@ -256,8 +205,7 @@ func (s *BoltStateDB) PutTaskRunnerLocalState(allocID, taskName string, val inte
 			return fmt.Errorf("failed to retrieve allocation bucket: %v", err)
 		}
 
-		path := strings.Join([]string{allocID, taskName, string(taskLocalStateKey)}, "-")
-		if err := s.codec.Put(taskBkt, path, taskLocalStateKey, val); err != nil {
+		if err := s.codec.Put(taskBkt, taskLocalStateKey, val); err != nil {
 			return fmt.Errorf("failed to write task_runner state: %v", err)
 		}
 
@@ -273,8 +221,42 @@ func (s *BoltStateDB) PutTaskState(allocID, taskName string, state *structs.Task
 			return fmt.Errorf("failed to retrieve allocation bucket: %v", err)
 		}
 
-		path := strings.Join([]string{allocID, taskName, string(taskStateKey)}, "-")
-		return s.codec.Put(taskBkt, path, taskStateKey, state)
+		return s.codec.Put(taskBkt, taskStateKey, state)
+	})
+}
+
+// DeleteTaskBucket is used to delete a task bucket if it exists.
+func (s *BoltStateDB) DeleteTaskBucket(allocID, taskName string) error {
+	return s.db.Update(func(tx *bolt.Tx) error {
+		// Retrieve the root allocations bucket
+		allocations := newNamedBucket(tx, allocationsBucket)
+		if allocations == nil {
+			return nil
+		}
+
+		// Retrieve the specific allocations bucket
+		alloc := allocations.Bucket([]byte(allocID))
+		if alloc == nil {
+			return nil
+		}
+
+		// Check if the bucket exists
+		key := []byte(taskName)
+		return s.codec.DeleteBucket(alloc, key)
+	})
+}
+
+// DeleteAllocationBucket is used to delete an allocation bucket if it exists.
+func (s *BoltStateDB) DeleteAllocationBucket(allocID string) error {
+	return s.db.Update(func(tx *bolt.Tx) error {
+		// Retrieve the root allocations bucket
+		allocations := newNamedBucket(tx, allocationsBucket)
+		if allocations == nil {
+			return nil
+		}
+
+		key := []byte(allocID)
+		return s.codec.DeleteBucket(allocations, key)
 	})
 }
 
@@ -288,18 +270,18 @@ func (s *BoltStateDB) Close() error {
 // particular allocation. If the root allocation bucket or the specific
 // allocation bucket doesn't exist, it will be created as long as the
 // transaction is writable.
-func getAllocationBucket(tx *bolt.Tx, allocID string) (*bolt.Bucket, error) {
+func getAllocationBucket(tx *bolt.Tx, allocID string) (kvStore, error) {
 	var err error
 	w := tx.Writable()
 
 	// Retrieve the root allocations bucket
-	allocations := tx.Bucket(allocationsBucket)
+	allocations := newNamedBucket(tx, allocationsBucket)
 	if allocations == nil {
 		if !w {
 			return nil, fmt.Errorf("Allocations bucket doesn't exist and transaction is not writable")
 		}
 
-		allocations, err = tx.CreateBucket(allocationsBucket)
+		allocations, err = createNamedBucketIfNotExists(tx, allocationsBucket)
 		if err != nil {
 			return nil, err
 		}
@@ -326,7 +308,7 @@ func getAllocationBucket(tx *bolt.Tx, allocID string) (*bolt.Bucket, error) {
 // particular task. If the root allocation bucket, the specific
 // allocation or task bucket doesn't exist, they will be created as long as the
 // transaction is writable.
-func getTaskBucket(tx *bolt.Tx, allocID, taskName string) (*bolt.Bucket, error) {
+func getTaskBucket(tx *bolt.Tx, allocID, taskName string) (kvStore, error) {
 	alloc, err := getAllocationBucket(tx, allocID)
 	if err != nil {
 		return nil, err