[FAB-16026] Convert RetrievedPvtdata to interface

* This will be necessary for consumers utilizing other interfaces in
ledger interface

Change-Id: Icbbb0b008c178cc03695f7971e41b1db459aade3
Signed-off-by: Danny Cao <dcao@us.ibm.com>

Author: caod123

core/ledger/ledger_interface.go

@@ -646,6 +646,13 @@ type Hasher interface {
 	Hash(msg []byte, opts bccsp.HashOpts) (hash []byte, err error)
 }
 
+// RetrievedPvtdata is a dependency that is implemented by coordinator/gossip for ledger
+// to be able to purge the transactions from the block after retrieving private data
+type RetrievedPvtdata interface {
+	GetBlockPvtdata() *BlockPvtdata
+	Purge()
+}
+
 // TxPvtdataInfo captures information about the requested private data to be retrieved
 // and is populated by ledger during commit
 type TxPvtdataInfo struct {

gossip/privdata/pvtdataprovider.go

@@ -44,6 +44,11 @@ type RetrievedPvtdata struct {
 	transientBlockRetention uint64
 }
 
+// GetBlockPvtdata returns the BlockPvtdata
+func (r *RetrievedPvtdata) GetBlockPvtdata() *ledger.BlockPvtdata {
+	return r.blockPvtdata
+}
+
 // Purge purges transactions in the block
 func (r *RetrievedPvtdata) Purge() {
 	purgeStart := time.Now()

gossip/privdata/pvtdataprovider_test.go

@@ -484,7 +484,7 @@ func testRetrievePrivateDataSuccess(t *testing.T,
 	expectedBlockPvtdata := formatExpectedBlockPvtdata(expectedRwSets)
 	// sometimes the collection private write sets are added out of order
 	// so we need to sort it to check equality with expected
-	blockPvtdata := sortBlockPvtdata(retrievedPvtdata.blockPvtdata)
+	blockPvtdata := sortBlockPvtdata(retrievedPvtdata.GetBlockPvtdata())
 	assert.Equal(t, expectedBlockPvtdata, blockPvtdata, scenario)
 
 	// Test pvtdata is purged from store on Done() call
@@ -567,12 +567,12 @@ func setupPrivateDataProvider(t *testing.T,
 
 func testPurged(t *testing.T,
 	scenario string,
-	retrievedPvtdata *RetrievedPvtdata,
+	retrievedPvtdata ledger.RetrievedPvtdata,
 	store *transientstore.Store,
 	txPvtdataInfo []*ledger.TxPvtdataInfo) {
 
 	retrievedPvtdata.Purge()
-	for _, pvtdata := range retrievedPvtdata.blockPvtdata.PvtData {
+	for _, pvtdata := range retrievedPvtdata.GetBlockPvtdata().PvtData {
 		func() {
 			txID := getTxIDBySeqInBlock(pvtdata.SeqInBlock, txPvtdataInfo)
 			require.NotEqual(t, txID, "", fmt.Sprintf("Could not find txID for SeqInBlock %d", pvtdata.SeqInBlock), scenario)