blockcache: respond to PR review comments

This commit embeds the mutex into the mockChainBackend struct,
unexports the getter by appending the prefix `get` to the method
name and undoes the split of GetBlock into two methods, which
breaks the atomicity of the GetBlock call.

Simplifies GetBlock docstring and removes docstring for the
getter.

blockcache/blockcache_test.go

@@ -26,33 +26,13 @@ func newMockChain() *mockChainBackend {
 	}
 }
 
-// GetBlock is a mock block fetching implementation, it increments chainCallCount
-// to track the number of backend calls and returns the block found in the internal
-// map of blocks.
+// GetBlock is a mock implementation of block fetching that tracks the number
+// of backend calls and returns the block found for the given hash or an error.
 func (m *mockChainBackend) GetBlock(blockHash *chainhash.Hash) (*wire.MsgBlock, error) {
-	m.incrementCallCount()
-	return m.getBlock(blockHash)
-}
-
-// ChainCallCount is a getter for the chainCallCount property.
-func (m *mockChainBackend) ChainCallCount() int {
-	m.RLock()
-	defer m.RUnlock()
-
-	return m.chainCallCount
-}
-
-func (m *mockChainBackend) addBlock(block *wire.MsgBlock, nonce uint32) {
 	m.Lock()
 	defer m.Unlock()
-	block.Header.Nonce = nonce
-	hash := block.Header.BlockHash()
-	m.blocks[hash] = block
-}
 
-func (m *mockChainBackend) getBlock(blockHash *chainhash.Hash) (*wire.MsgBlock, error) {
-	m.RLock()
-	defer m.RUnlock()
+	m.chainCallCount++
 
 	block, ok := m.blocks[*blockHash]
 
@@ -63,11 +43,19 @@ func (m *mockChainBackend) getBlock(blockHash *chainhash.Hash) (*wire.MsgBlock,
 	return block, nil
 }
 
-func (m *mockChainBackend) incrementCallCount() {
+func (m *mockChainBackend) getChainCallCount() int {
+	m.RLock()
+	defer m.RUnlock()
+
+	return m.chainCallCount
+}
+
+func (m *mockChainBackend) addBlock(block *wire.MsgBlock, nonce uint32) {
 	m.Lock()
 	defer m.Unlock()
-
-	m.chainCallCount++
+	block.Header.Nonce = nonce
+	hash := block.Header.BlockHash()
+	m.blocks[hash] = block
 }
 
 func (m *mockChainBackend) resetChainCallCount() {
@@ -114,7 +102,7 @@ func TestBlockCacheGetBlock(t *testing.T) {
 	_, err := bc.GetBlock(&blockhash1, getBlockImpl)
 	require.NoError(t, err)
 	require.Equal(t, 1, bc.Cache.Len())
-	require.Equal(t, 1, mc.ChainCallCount())
+	require.Equal(t, 1, mc.getChainCallCount())
 	mc.resetChainCallCount()
 
 	_, err = bc.Cache.Get(*inv1)
@@ -126,7 +114,7 @@ func TestBlockCacheGetBlock(t *testing.T) {
 	_, err = bc.GetBlock(&blockhash2, getBlockImpl)
 	require.NoError(t, err)
 	require.Equal(t, 2, bc.Cache.Len())
-	require.Equal(t, 1, mc.ChainCallCount())
+	require.Equal(t, 1, mc.getChainCallCount())
 	mc.resetChainCallCount()
 
 	_, err = bc.Cache.Get(*inv1)
@@ -141,7 +129,7 @@ func TestBlockCacheGetBlock(t *testing.T) {
 	_, err = bc.GetBlock(&blockhash1, getBlockImpl)
 	require.NoError(t, err)
 	require.Equal(t, 2, bc.Cache.Len())
-	require.Equal(t, 0, mc.ChainCallCount())
+	require.Equal(t, 0, mc.getChainCallCount())
 	mc.resetChainCallCount()
 
 	// Since the Cache is now at its max capacity, it is expected that when
@@ -152,7 +140,7 @@ func TestBlockCacheGetBlock(t *testing.T) {
 	_, err = bc.GetBlock(&blockhash3, getBlockImpl)
 	require.NoError(t, err)
 	require.Equal(t, 2, bc.Cache.Len())
-	require.Equal(t, 1, mc.ChainCallCount())
+	require.Equal(t, 1, mc.getChainCallCount())
 	mc.resetChainCallCount()
 
 	_, err = bc.Cache.Get(*inv1)
@@ -207,5 +195,5 @@ func TestBlockCacheMutexes(t *testing.T) {
 	}
 
 	wg.Wait()
-	require.Equal(t, 2, mc.ChainCallCount())
+	require.Equal(t, 2, mc.getChainCallCount())
 }