MM-10702 Moving plugins to use hashicorp go-plugin. (#8978)

* Moving plugins to use hashicorp go-plugin.

* Tweaks from feedback.

1 files changed, 96 insertions, 0 deletions

diff --git a/vendor/google.golang.org/grpc/backoff.go b/vendor/google.golang.org/grpc/backoff.go
new file mode 100644
index 000000000..c40facce5
--- /dev/null
+++ b/vendor/google.golang.org/grpc/backoff.go
@@ -0,0 +1,96 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+	"math/rand"
+	"time"
+)
+
+// DefaultBackoffConfig uses values specified for backoff in
+// https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md.
+var DefaultBackoffConfig = BackoffConfig{
+	MaxDelay:  120 * time.Second,
+	baseDelay: 1.0 * time.Second,
+	factor:    1.6,
+	jitter:    0.2,
+}
+
+// backoffStrategy defines the methodology for backing off after a grpc
+// connection failure.
+//
+// This is unexported until the gRPC project decides whether or not to allow
+// alternative backoff strategies. Once a decision is made, this type and its
+// method may be exported.
+type backoffStrategy interface {
+	// backoff returns the amount of time to wait before the next retry given
+	// the number of consecutive failures.
+	backoff(retries int) time.Duration
+}
+
+// BackoffConfig defines the parameters for the default gRPC backoff strategy.
+type BackoffConfig struct {
+	// MaxDelay is the upper bound of backoff delay.
+	MaxDelay time.Duration
+
+	// TODO(stevvooe): The following fields are not exported, as allowing
+	// changes would violate the current gRPC specification for backoff. If
+	// gRPC decides to allow more interesting backoff strategies, these fields
+	// may be opened up in the future.
+
+	// baseDelay is the amount of time to wait before retrying after the first
+	// failure.
+	baseDelay time.Duration
+
+	// factor is applied to the backoff after each retry.
+	factor float64
+
+	// jitter provides a range to randomize backoff delays.
+	jitter float64
+}
+
+func setDefaults(bc *BackoffConfig) {
+	md := bc.MaxDelay
+	*bc = DefaultBackoffConfig
+
+	if md > 0 {
+		bc.MaxDelay = md
+	}
+}
+
+func (bc BackoffConfig) backoff(retries int) time.Duration {
+	if retries == 0 {
+		return bc.baseDelay
+	}
+	backoff, max := float64(bc.baseDelay), float64(bc.MaxDelay)
+	for backoff < max && retries > 0 {
+		backoff *= bc.factor
+		retries--
+	}
+	if backoff > max {
+		backoff = max
+	}
+	// Randomize backoff delays so that if a cluster of requests start at
+	// the same time, they won't operate in lockstep.
+	backoff *= 1 + bc.jitter*(rand.Float64()*2-1)
+	if backoff < 0 {
+		return 0
+	}
+	return time.Duration(backoff)
+}