start of v3

Author: Nick Randall

.gitignore

@@ -0,0 +1 @@
+vendor/

Gopkg.lock

@@ -0,0 +1,34 @@
+
+# Gopkg.toml example
+#
+# Refer to https://github.com/golang/dep/blob/master/docs/Gopkg.toml.md
+# for detailed Gopkg.toml documentation.
+#
+# required = ["github.com/user/thing/cmd/thing"]
+# ignored = ["github.com/user/project/pkgX", "bitbucket.org/user/project/pkgA/pkgY"]
+#
+# [[constraint]]
+#   name = "github.com/user/project"
+#   version = "1.0.0"
+#
+# [[constraint]]
+#   name = "github.com/user/project2"
+#   branch = "dev"
+#   source = "github.com/myfork/project2"
+#
+# [[override]]
+#  name = "github.com/x/y"
+#  version = "2.4.0"
+
+
+[[constraint]]
+  branch = "master"
+  name = "github.com/hashicorp/golang-lru"
+
+[[constraint]]
+  name = "github.com/opentracing/opentracing-go"
+  version = "1.0.2"
+
+[[constraint]]
+  name = "github.com/patrickmn/go-cache"
+  version = "2.1.0"

Gopkg.toml

@@ -40,7 +40,7 @@ if err != nil {
 log.Printf("value: %#v", result)
 ```
 
-## Upgrade from v1
+## Upgrade from v1 to v2
 The only difference between v1 and v2 is that we added use of [context](https://golang.org/pkg/context).
 
 ```diff
@@ -55,6 +55,29 @@ The only difference between v1 and v2 is that we added use of [context](https://
 + type BatchFunc func(context.Context, []string) []*Result
 ```
 
+## Upgrade from v2 to v3
+```diff
+// dataloader.Interface as added context.Context to methods
+- loader.Prime(key string, value interface{}) Interface
++ loader.Prime(ctx context.Context, key string, value interface{}) Interface
+- loader.Clear(key string) Interface
++ loader.Clear(ctx context.Context, key string) Interface
+```
+
+```diff
+// cache interface as added context.Context to methods
+type Cache interface {
+-	Get(string) (Thunk, bool)
++	Get(context.Context, string) (Thunk, bool)
+-	Set(string, Thunk)
++	Set(context.Context, string, Thunk)
+-	Delete(string) bool
++	Delete(context.Context, string) bool
+	Clear()
+}
+```
+
+
 ### Don't need/want to use context?
 You're welcome to install the v1 version of this library.
 

README.md

@@ -1,10 +1,12 @@
 package dataloader
 
+import "context"
+
 // The Cache interface. If a custom cache is provided, it must implement this interface.
 type Cache interface {
-	Get(string) (Thunk, bool)
-	Set(string, Thunk)
-	Delete(string) bool
+	Get(context.Context, string) (Thunk, bool)
+	Set(context.Context, string, Thunk)
+	Delete(context.Context, string) bool
 	Clear()
 }
 
@@ -14,13 +16,13 @@ type Cache interface {
 type NoCache struct{}
 
 // Get is a NOOP
-func (c *NoCache) Get(string) (Thunk, bool) { return nil, false }
+func (c *NoCache) Get(context.Context, string) (Thunk, bool) { return nil, false }
 
 // Set is a NOOP
-func (c *NoCache) Set(string, Thunk) { return }
+func (c *NoCache) Set(context.Context, string, Thunk) { return }
 
 // Delete is a NOOP
-func (c *NoCache) Delete(string) bool { return false }
+func (c *NoCache) Delete(context.Context, string) bool { return false }
 
 // Clear is a NOOP
 func (c *NoCache) Clear() { return }

cache.go

@@ -22,9 +22,9 @@ import (
 type Interface interface {
 	Load(context.Context, string) Thunk
 	LoadMany(context.Context, []string) ThunkMany
-	Clear(string) Interface
+	Clear(context.Context, string) Interface
 	ClearAll() Interface
-	Prime(key string, value interface{}) Interface
+	Prime(ctx context.Context, key string, value interface{}) Interface
 }
 
 // BatchFunc is a function, which when given a slice of keys (string), returns an slice of `results`.
@@ -193,6 +193,7 @@ func NewBatchedLoader(batchFn BatchFunc, opts ...Option) *Loader {
 // Load load/resolves the given key, returning a channel that will contain the value and error
 func (l *Loader) Load(originalContext context.Context, key string) Thunk {
 	ctx, finish := l.tracer.TraceLoad(originalContext, key)
+
 	c := make(chan *Result, 1)
 	var result struct {
 		mu    sync.RWMutex
@@ -201,7 +202,7 @@ func (l *Loader) Load(originalContext context.Context, key string) Thunk {
 
 	// lock to prevent duplicate keys coming in before item has been added to cache.
 	l.cacheLock.Lock()
-	if v, ok := l.cache.Get(key); ok {
+	if v, ok := l.cache.Get(ctx, key); ok {
 		defer finish(v)
 		defer l.cacheLock.Unlock()
 		return v
@@ -223,8 +224,9 @@ func (l *Loader) Load(originalContext context.Context, key string) Thunk {
 		defer result.mu.RUnlock()
 		return result.value.Data, result.value.Error
 	}
+	defer finish(thunk)
 
-	l.cache.Set(key, thunk)
+	l.cache.Set(ctx, key, thunk)
 	l.cacheLock.Unlock()
 
 	// this is sent to batch fn. It contains the key and the channel to return the
@@ -236,7 +238,7 @@ func (l *Loader) Load(originalContext context.Context, key string) Thunk {
 	if l.curBatcher == nil {
 		l.curBatcher = l.newBatcher(l.silent, l.tracer)
 		// start the current batcher batch function
-		go l.curBatcher.batch(ctx)
+		go l.curBatcher.batch(originalContext)
 		// start a sleeper for the current batcher
 		l.endSleeper = make(chan bool)
 		go l.sleeper(l.curBatcher, l.endSleeper)
@@ -261,13 +263,13 @@ func (l *Loader) Load(originalContext context.Context, key string) Thunk {
 	}
 	l.batchLock.Unlock()
 
-	defer finish(thunk)
 	return thunk
 }
 
 // LoadMany loads mulitiple keys, returning a thunk (type: ThunkMany) that will resolve the keys passed in.
 func (l *Loader) LoadMany(originalContext context.Context, keys []string) ThunkMany {
 	ctx, finish := l.tracer.TraceLoadMany(originalContext, keys)
+
 	length := len(keys)
 	data := make([]interface{}, length)
 	errors := make([]error, length)
@@ -276,13 +278,13 @@ func (l *Loader) LoadMany(originalContext context.Context, keys []string) ThunkM
 
 	wg.Add(length)
 	for i := range keys {
-		go func(i int) {
+		go func(ctx context.Context, i int) {
 			defer wg.Done()
 			thunk := l.Load(ctx, keys[i])
 			result, err := thunk()
 			data[i] = result
 			errors[i] = err
-		}(i)
+		}(ctx, i)
 	}
 
 	go func() {
@@ -318,9 +320,9 @@ func (l *Loader) LoadMany(originalContext context.Context, keys []string) ThunkM
 }
 
 // Clear clears the value at `key` from the cache, it it exsits. Returs self for method chaining
-func (l *Loader) Clear(key string) Interface {
+func (l *Loader) Clear(ctx context.Context, key string) Interface {
 	l.cacheLock.Lock()
-	l.cache.Delete(key)
+	l.cache.Delete(ctx, key)
 	l.cacheLock.Unlock()
 	return l
 }
@@ -336,12 +338,12 @@ func (l *Loader) ClearAll() Interface {
 
 // Prime adds the provided key and value to the cache. If the key already exists, no change is made.
 // Returns self for method chaining
-func (l *Loader) Prime(key string, value interface{}) Interface {
-	if _, ok := l.cache.Get(key); !ok {
+func (l *Loader) Prime(ctx context.Context, key string, value interface{}) Interface {
+	if _, ok := l.cache.Get(ctx, key); !ok {
 		thunk := func() (interface{}, error) {
 			return value, nil
 		}
-		l.cache.Set(key, thunk)
+		l.cache.Set(ctx, key, thunk)
 	}
 	return l
 }

dataloader.go

@@ -250,8 +250,8 @@ func TestLoader(t *testing.T) {
 	t.Run("allows primed cache", func(t *testing.T) {
 		t.Parallel()
 		identityLoader, loadCalls := IDLoader(0)
-		identityLoader.Prime("A", "Cached")
 		ctx := context.Background()
+		identityLoader.Prime(ctx, "A", "Cached")
 		future1 := identityLoader.Load(ctx, "1")
 		future2 := identityLoader.Load(ctx, "A")
 
@@ -280,10 +280,10 @@ func TestLoader(t *testing.T) {
 		t.Parallel()
 		identityLoader, loadCalls := IDLoader(0)
 		ctx := context.Background()
-		identityLoader.Prime("A", "Cached")
-		identityLoader.Prime("B", "B")
+		identityLoader.Prime(ctx, "A", "Cached")
+		identityLoader.Prime(ctx, "B", "B")
 		future1 := identityLoader.Load(ctx, "1")
-		future2 := identityLoader.Clear("A").Load(ctx, "A")
+		future2 := identityLoader.Clear(ctx, "A").Load(ctx, "A")
 		future3 := identityLoader.Load(ctx, "B")
 
 		_, err := future1()
@@ -334,7 +334,7 @@ func TestLoader(t *testing.T) {
 			t.Errorf("did not batch queries. Expected %#v, got %#v", expected, calls)
 		}
 
-		if _, found := batchOnlyLoader.cache.Get("1"); found {
+		if _, found := batchOnlyLoader.cache.Get(ctx, "1"); found {
 			t.Errorf("did not clear cache after batch. Expected %#v, got %#v", false, found)
 		}
 	})
@@ -343,8 +343,8 @@ func TestLoader(t *testing.T) {
 		t.Parallel()
 		identityLoader, loadCalls := IDLoader(0)
 		ctx := context.Background()
-		identityLoader.Prime("A", "Cached")
-		identityLoader.Prime("B", "B")
+		identityLoader.Prime(ctx, "A", "Cached")
+		identityLoader.Prime(ctx, "B", "B")
 
 		identityLoader.ClearAll()
 
@@ -377,12 +377,12 @@ func TestLoader(t *testing.T) {
 		t.Parallel()
 		identityLoader, loadCalls := NoCacheLoader(0)
 		ctx := context.Background()
-		identityLoader.Prime("A", "Cached")
-		identityLoader.Prime("B", "B")
+		identityLoader.Prime(ctx, "A", "Cached")
+		identityLoader.Prime(ctx, "B", "B")
 
 		identityLoader.ClearAll()
 
-		future1 := identityLoader.Clear("1").Load(ctx, "1")
+		future1 := identityLoader.Clear(ctx, "1").Load(ctx, "1")
 		future2 := identityLoader.Load(ctx, "A")
 		future3 := identityLoader.Load(ctx, "B")
 
@@ -411,8 +411,8 @@ func TestLoader(t *testing.T) {
 		t.Parallel()
 		identityLoader, loadCalls := NoCacheLoader(0)
 		ctx := context.Background()
-		identityLoader.Prime("A", "Cached")
-		identityLoader.Prime("B", "B")
+		identityLoader.Prime(ctx, "A", "Cached")
+		identityLoader.Prime(ctx, "B", "B")
 
 		future1 := identityLoader.Load(ctx, "1")
 		future2 := identityLoader.Load(ctx, "A")

dataloader_test.go

@@ -2,7 +2,10 @@
 
 package dataloader
 
-import "sync"
+import (
+	"context"
+	"sync"
+)
 
 // InMemoryCache is an in memory implementation of Cache interface.
 // this simple implementation is well suited for
@@ -23,15 +26,15 @@ func NewCache() *InMemoryCache {
 }
 
 // Set sets the `value` at `key` in the cache
-func (c *InMemoryCache) Set(key string, value Thunk) {
+func (c *InMemoryCache) Set(_ context.Context, key string, value Thunk) {
 	c.mu.Lock()
 	c.items[key] = value
 	c.mu.Unlock()
 }
 
 // Get gets the value at `key` if it exsits, returns value (or nil) and bool
 // indicating of value was found
-func (c *InMemoryCache) Get(key string) (Thunk, bool) {
+func (c *InMemoryCache) Get(_ context.Context, key string) (Thunk, bool) {
 	c.mu.RLock()
 	defer c.mu.RUnlock()
 
@@ -44,7 +47,7 @@ func (c *InMemoryCache) Get(key string) (Thunk, bool) {
 }
 
 // Delete deletes item at `key` from cache
-func (c *InMemoryCache) Delete(key string) bool {
+func (c *InMemoryCache) Delete(_ context.Context, key string) bool {
 	if _, found := c.Get(key); found {
 		c.mu.Lock()
 		defer c.mu.Unlock()