From fb908275328cb482a62f3eccb5a6902ca892b9b7 Mon Sep 17 00:00:00 2001
From: Alex Vanin <alexey@nspcc.ru>
Date: Wed, 18 Nov 2020 16:01:59 +0300
Subject: [PATCH] [#184] Add SDK client cache package
With this package we can reuse already created connections.
Later on neofs-api-go will support checking connection health
and `Close` operation, so this cache could run worker and remove
unhealthy clients.
Signed-off-by: Alex Vanin <alexey@nspcc.ru>
---
pkg/network/cache/client.go | 69 +++++++++++++++++++++++++++++++++++++
1 file changed, 69 insertions(+)
create mode 100644 pkg/network/cache/client.go
diff --git a/pkg/network/cache/client.go b/pkg/network/cache/client.go
new file mode 100644
index 000000000..136b84dea
--- /dev/null
+++ b/pkg/network/cache/client.go
@@ -0,0 +1,69 @@
+package cache
+
+import (
+ "crypto/ecdsa"
+ "crypto/sha256"
+ "encoding/hex"
+ "sync"
+
+ "github.com/nspcc-dev/neofs-api-go/pkg/client"
+ crypto "github.com/nspcc-dev/neofs-crypto"
+)
+
+type (
+ // ClientCache is a structure around neofs-api-go/pkg/client to reuse
+ // already created clients.
+ ClientCache struct {
+ mu *sync.RWMutex
+ clients map[string]*client.Client
+ }
+)
+
+// NewSDKClientCache creates instance of client cache.
+func NewSDKClientCache() *ClientCache {
+ return &ClientCache{
+ mu: new(sync.RWMutex),
+ clients: make(map[string]*client.Client),
+ }
+}
+
+// Get function returns existing client or creates a new one. Consider passing
+// connection options to specify details for client, but don't forget that two
+// different set of options should provide two different clients.
+func (c *ClientCache) Get(key *ecdsa.PrivateKey, address string) (*client.Client, error) {
+ id := uniqueID(key, address)
+
+ c.mu.RLock()
+ if cli, ok := c.clients[id]; ok {
+ // todo: check underlying connection neofs-api-go#196
+ c.mu.RUnlock()
+
+ return cli, nil
+ }
+
+ c.mu.RUnlock()
+ // if client is not found in cache, then create a new one
+ c.mu.Lock()
+ defer c.mu.Unlock()
+
+ // check once again if client is missing in cache, concurrent routine could
+ // create client while this routine was locked on `c.mu.Lock()`.
+ if cli, ok := c.clients[id]; ok {
+ return cli, nil
+ }
+
+ cli, err := client.New(key, client.WithAddress(address))
+ if err != nil {
+ return nil, err
+ }
+
+ c.clients[id] = cli
+
+ return cli, nil
+}
+
+func uniqueID(key *ecdsa.PrivateKey, address string) string {
+ keyFingerprint := sha256.Sum256(crypto.MarshalPrivateKey(key))
+
+ return hex.EncodeToString(keyFingerprint[:]) + address
+}