Fix bugs, refactor, document and land the weighted consistent hashing branch

caboose.go

@@ -13,30 +13,44 @@ import (
 )
 
 type Config struct {
+	// OrchestratorEndpoint is the URL of the Saturn orchestrator.
 	OrchestratorEndpoint url.URL
-	OrchestratorClient   *http.Client
+	// OrchestratorClient is the HTTP client to use when communicating with the Saturn orchestrator.
+	OrchestratorClient *http.Client
 
+	// LoggingEndpoint is the URL of the logging endpoint where we submit logs pertaining to our Saturn retrieval requests.
 	LoggingEndpoint url.URL
-	LoggingClient   *http.Client
+	// LoggingClient is the HTTP client to use when communicating with the logging endpoint.
+	LoggingClient *http.Client
+	// LoggingInterval is the interval at which we submit logs to the logging endpoint.
 	LoggingInterval time.Duration
 
-	Client       *http.Client
+	// SaturnClient is the HTTP client to use when retrieving content from the Saturn network.
+	SaturnClient *http.Client
 	ExtraHeaders *http.Header
 
-	DoValidation                bool
-	AffinityKey                 string
-	PoolRefresh                 time.Duration
-	PoolFailureDownvoteDebounce time.Duration
-	PoolMaxSize                 int
+	// DoValidation is used to determine if we should validate the blocks recieved from the Saturn network.
+	DoValidation bool
+	// If set, AffinityKey is used instead of the block cid as the key on the Saturn node pool
+	// to determine which Saturn node to retrieve the block from.
+	AffinityKey string
+	// PoolRefresh is the interval at which we refresh the pool of Saturn nodes.
+	PoolRefresh time.Duration
+
+	// PoolWeightChangeDebounce is the amount of time we wait between consecutive updates to the weight of a Saturn node
+	// in our pool after a retrieval success/failure.
+	PoolWeightChangeDebounce time.Duration
+
 	// trigger early refreshes when pool size drops below this low watermark
 	PoolLowWatermark int
-	MaxConcurrency   int
-	MaxRetries       int
+	// MaxRetrievalAttempts determines the number of times we will attempt to retrieve a block from the Saturn network before failing.
+	MaxRetrievalAttempts int
 }
 
 const DefaultMaxRetries = 3
 const DefaultPoolFailureDownvoteDebounce = time.Second
 const DefaultPoolLowWatermark = 5
+const DefaultSaturnRequestTimeout = 19 * time.Second
 
 var ErrNotImplemented error = errors.New("not implemented")
 var ErrNoBackend error = errors.New("no available backend")
@@ -54,17 +68,19 @@ func NewCaboose(config *Config) (ipfsblockstore.Blockstore, error) {
 		logger: newLogger(config),
 	}
 	c.pool.logger = c.logger
-	if c.config.Client == nil {
-		c.config.Client = http.DefaultClient
+	if c.config.SaturnClient == nil {
+		c.config.SaturnClient = &http.Client{
+			Timeout: DefaultSaturnRequestTimeout,
+		}
 	}
-	if c.config.PoolFailureDownvoteDebounce == 0 {
-		c.config.PoolFailureDownvoteDebounce = DefaultPoolFailureDownvoteDebounce
+	if c.config.PoolWeightChangeDebounce == 0 {
+		c.config.PoolWeightChangeDebounce = DefaultPoolFailureDownvoteDebounce
 	}
 	if c.config.PoolLowWatermark == 0 {
 		c.config.PoolLowWatermark = DefaultPoolLowWatermark
 	}
-	if c.config.MaxRetries == 0 {
-		c.config.MaxRetries = DefaultMaxRetries
+	if c.config.MaxRetrievalAttempts == 0 {
+		c.config.MaxRetrievalAttempts = DefaultMaxRetries
 	}
 	return &c, nil
 }
@@ -74,32 +90,19 @@ func (c *Caboose) Close() {
 	c.logger.Close()
 }
 
+// Note: Caboose is NOT a persistent blockstore and does NOT have an in-memory cache. Every block read request will escape to the Saturn network.
+// Caching is left to the caller.
+
 func (c *Caboose) Has(ctx context.Context, it cid.Cid) (bool, error) {
-	aff := ctx.Value(c.config.AffinityKey)
-	if aff != nil {
-		blk, err := c.pool.fetchWith(ctx, it, aff.(string))
-		if err != nil {
-			return false, err
-		}
-		return blk != nil, nil
-	}
-	blk, err := c.pool.fetchWith(ctx, it, "")
+	blk, err := c.pool.fetchWith(ctx, it, c.getAffinity(ctx))
 	if err != nil {
 		return false, err
 	}
 	return blk != nil, nil
 }
 
 func (c *Caboose) Get(ctx context.Context, it cid.Cid) (blocks.Block, error) {
-	aff := ctx.Value(c.config.AffinityKey)
-	if aff != nil {
-		blk, err := c.pool.fetchWith(ctx, it, aff.(string))
-		if err != nil {
-			return nil, err
-		}
-		return blk, nil
-	}
-	blk, err := c.pool.fetchWith(ctx, it, "")
+	blk, err := c.pool.fetchWith(ctx, it, c.getAffinity(ctx))
 	if err != nil {
 		return nil, err
 	}
@@ -108,21 +111,20 @@ func (c *Caboose) Get(ctx context.Context, it cid.Cid) (blocks.Block, error) {
 
 // GetSize returns the CIDs mapped BlockSize
 func (c *Caboose) GetSize(ctx context.Context, it cid.Cid) (int, error) {
-	aff := ctx.Value(c.config.AffinityKey)
-	if aff != nil {
-		blk, err := c.pool.fetchWith(ctx, it, aff.(string))
-		if err != nil {
-			return 0, err
-		}
-		return len(blk.RawData()), nil
-	}
-	blk, err := c.pool.fetchWith(ctx, it, "")
+	blk, err := c.pool.fetchWith(ctx, it, c.getAffinity(ctx))
 	if err != nil {
 		return 0, err
 	}
 	return len(blk.RawData()), nil
 }
 
+func (c *Caboose) getAffinity(ctx context.Context) string {
+	if affC := ctx.Value(c.config.AffinityKey); affC != nil {
+		return affC.(string)
+	}
+	return ""
+}
+
 // HashOnRead specifies if every read block should be
 // rehashed to make sure it matches its CID.
 func (c *Caboose) HashOnRead(enabled bool) {

cmd/caboose/main.go

@@ -50,15 +50,17 @@ func main1() int {
 
 			cb, err := caboose.NewCaboose(&caboose.Config{
 				OrchestratorEndpoint: *oe,
-				OrchestratorClient:   http.DefaultClient,
+				OrchestratorClient: &http.Client{
+					Timeout: 30 * time.Second,
+				},
 
 				LoggingEndpoint: *le,
 				LoggingClient:   http.DefaultClient,
 				LoggingInterval: 5 * time.Second,
 
 				DoValidation: true,
 				PoolRefresh:  5 * time.Minute,
-				Client:       &saturnClient,
+				SaturnClient: &saturnClient,
 			})
 			if err != nil {
 				return err

failure_test.go

@@ -43,11 +43,11 @@ func TestCabooseFailures(t *testing.T) {
 		LoggingClient:        http.DefaultClient,
 		LoggingInterval:      time.Hour,
 
-		Client:                      http.DefaultClient,
-		DoValidation:                false,
-		PoolFailureDownvoteDebounce: time.Duration(1),
-		PoolRefresh:                 time.Millisecond * 50,
-		MaxRetries:                  2,
+		SaturnClient:             http.DefaultClient,
+		DoValidation:             false,
+		PoolWeightChangeDebounce: time.Duration(1),
+		PoolRefresh:              time.Millisecond * 50,
+		MaxRetrievalAttempts:     2,
 	})
 	if err != nil {
 		t.Fatal(err)