From 6064c80250f32dfc55a7bfd6113f4ed87c3fcd97 Mon Sep 17 00:00:00 2001
From: "Paul W. Homer" <paul_homer@yahoo.com>
Date: Thu, 23 Mar 2017 11:37:46 -0400
Subject: [PATCH] Modified all db types to conform to the interface changes.

---
 c_level_db.go  | 17 +++++++++++++++++
 db.go          |  5 +++--
 go_level_db.go | 32 +++++++++++++++++++++++++-------
 mem_db.go      | 49 +++++++++++++++++++++++++++++++++++++++++++------
 4 files changed, 88 insertions(+), 15 deletions(-)

diff --git a/c_level_db.go b/c_level_db.go
index 6c87c294..41ed4dc1 100644
--- a/c_level_db.go
+++ b/c_level_db.go
@@ -106,6 +106,23 @@ func (db *CLevelDB) Print() {
 	}
 }
 
+func (db *CLevelDB) Stats() map[string]string {
+	keys := []string{}
+
+	stats := make(map[string]string)
+	for _, key := range keys {
+		str, err := db.db.GetProperty(key)
+		if err == nil {
+			stats[key] = str
+		}
+	}
+	return stats
+}
+
+func (db *CLevelDB) Iterator() Iterator {
+	return db.db.NewIterator(nil, nil)
+}
+
 func (db *CLevelDB) NewBatch() Batch {
 	batch := levigo.NewWriteBatch()
 	return &cLevelDBBatch{db, batch}
diff --git a/db.go b/db.go
index 9cd4e1c2..b8849909 100644
--- a/db.go
+++ b/db.go
@@ -12,9 +12,9 @@ type DB interface {
 	NewBatch() Batch
 
 	// For debugging
-	Iterator() Iterator
-	Next(Iterator) (key []byte, value []byte)
 	Print()
+	Iterator() Iterator
+	Stats() map[string]string
 }
 
 type Batch interface {
@@ -25,6 +25,7 @@ type Batch interface {
 
 type Iterator interface {
 	Next() bool
+
 	Key() []byte
 	Value() []byte
 }
diff --git a/go_level_db.go b/go_level_db.go
index 3020d4a0..ac936d01 100644
--- a/go_level_db.go
+++ b/go_level_db.go
@@ -82,6 +82,9 @@ func (db *GoLevelDB) Close() {
 }
 
 func (db *GoLevelDB) Print() {
+	str, _ := db.db.GetProperty("leveldb.stats")
+	fmt.Printf("%v\n", str)
+
 	iter := db.db.NewIterator(nil, nil)
 	for iter.Next() {
 		key := iter.Key()
@@ -90,15 +93,30 @@ func (db *GoLevelDB) Print() {
 	}
 }
 
-func (db *GoLevelDB) Iterator() Iterator {
-	return db.db.NewIterator(nil, nil)
+func (db *GoLevelDB) Stats() map[string]string {
+	keys := []string{
+		"leveldb.num-files-at-level{n}",
+		"leveldb.stats",
+		"leveldb.sstables",
+		"leveldb.blockpool",
+		"leveldb.cachedblock",
+		"leveldb.openedtables",
+		"leveldb.alivesnaps",
+		"leveldb.alibeiters",
+	}
+
+	stats := make(map[string]string)
+	for _, key := range keys {
+		str, err := db.db.GetProperty(key)
+		if err == nil {
+			stats[key] = str
+		}
+	}
+	return stats
 }
 
-func (db *GoLevelDB) Next(iter Iterator) ([]byte, []byte) {
-	if iter.Next() {
-		return iter.Key(), iter.Value()
-	}
-	return nil, nil
+func (db *GoLevelDB) Iterator() Iterator {
+	return db.db.NewIterator(nil, nil)
 }
 
 func (db *GoLevelDB) NewBatch() Batch {
diff --git a/mem_db.go b/mem_db.go
index dcd86e6d..ef410e88 100644
--- a/mem_db.go
+++ b/mem_db.go
@@ -65,14 +65,51 @@ func (db *MemDB) Print() {
 	}
 }
 
-// TODO: needs to be wired to range db.db
-func (db *MemDB) Iterator() Iterator {
-	return nil
+func (db *MemDB) Stats() map[string]string {
+	stats := make(map[string]string)
+	stats["database.type"] = "memDB"
+	return stats
 }
 
-// TODO: needs to be wired to range db.db
-func (db *MemDB) Next(iter Iterator) (key []byte, value []byte) {
-	return nil, nil
+type memDBIterator struct {
+	last int
+	keys []string
+	db   *MemDB
+}
+
+func (it *memDBIterator) Create(db *MemDB) *memDBIterator {
+	if it == nil {
+		it = &memDBIterator{}
+	}
+	it.db = db
+	it.last = -1
+
+	// unfortunately we need a copy of all of the keys
+	for key, _ := range db.db {
+		it.keys = append(it.keys, key)
+	}
+	return it
+}
+
+func (it *memDBIterator) Next() bool {
+	if it.last >= len(it.keys) {
+		return false
+	}
+	it.last++
+	return true
+}
+
+func (it *memDBIterator) Key() []byte {
+	return []byte(it.keys[it.last])
+}
+
+func (it *memDBIterator) Value() []byte {
+	return it.db.db[it.keys[it.last]]
+}
+
+func (db *MemDB) Iterator() Iterator {
+	var it *memDBIterator
+	return it.Create(db)
 }
 
 func (db *MemDB) NewBatch() Batch {