Add Cursor.Next() to C cursor.

4 files changed, 228 insertions, 262 deletions

diff --git a/c/cursor.go b/c/cursor.go
index 73c5269..000dd9d 100644
--- a/c/cursor.go
+++ b/c/cursor.go
@@ -6,137 +6,190 @@ package c
 #include <stdio.h>
 #include <inttypes.h>
 
+//------------------------------------------------------------------------------
+// Constants
+//------------------------------------------------------------------------------
+
+// This represents the maximum number of levels that a cursor can traverse.
 #define MAX_DEPTH	100
-#define BRANCH_PAGE	1
+
+// These flags mark the type of page and are set in the page.flags.
+#define PAGE_BRANCH   0x01
+#define PAGE_LEAF     0x02
+#define PAGE_META     0x04
+#define PAGE_FREELIST 0x10
+
+
+//------------------------------------------------------------------------------
+// Typedefs
+//------------------------------------------------------------------------------
 
 // These types MUST have the same layout as their corresponding Go types
 
 typedef int64_t	pgid;
 
+// Page represents a header struct of a block in the mmap.
 typedef struct page {
-	pgid		id;
-	uint16_t	flags;
-	uint16_t	count;
-	uint32_t	overflow;
+	pgid     id;
+	uint16_t flags;
+	uint16_t count;
+	uint32_t overflow;
 } page;
 
-typedef struct branch_elem {
-	uint32_t	pos;
-	uint32_t	ksize;
-	pgid		page;
-} branch_elem;
-
-typedef struct leaf_elem {
-	uint32_t	flags;
-	uint32_t	pos;
-	uint32_t	ksize;
-	uint32_t	vsize;
-} leaf_elem;
-
-// private types
-
+// The branch element represents an a item in a branch page
+// that points to a child page.
+typedef struct branch_element {
+	uint32_t pos;
+	uint32_t ksize;
+	pgid     page;
+} branch_element;
+
+// The leaf element represents an a item in a leaf page
+// that points to a key/value pair.
+typedef struct leaf_element {
+	uint32_t flags;
+	uint32_t pos;
+	uint32_t ksize;
+	uint32_t vsize;
+} leaf_element;
+
+// elem_ref represents a pointer to an element inside of a page.
+// It is used by the cursor stack to track the position at each level.
 typedef struct elem_ref {
-	page	*page;
-	uint16_t	index;
+	page     *page;
+	uint16_t index;
 } elem_ref;
 
-// public types
-
+// bolt_val represents a pointer to a fixed-length series of bytes.
+// It is used to represent keys and values returned by the cursor.
 typedef struct bolt_val {
     uint32_t size;
     void     *data;
 } bolt_val;
 
+// bolt_cursor represents a cursor attached to a bucket.
 typedef struct bolt_cursor {
-	void			*data;
-	pgid			root;
-	size_t			pgsz;
-	unsigned int	stackp;
-	elem_ref		stack[MAX_DEPTH];
+	void     *data;
+	pgid     root;
+	size_t   pgsz;
+	int      top;
+	elem_ref stack[MAX_DEPTH];
 } bolt_cursor;
 
 
-// int bolt_cursor_seek(bolt_cursor *c, bolt_val *key, bolt_val *actual_key, bolt_val *value)
+//------------------------------------------------------------------------------
+// Forward Declarations
+//------------------------------------------------------------------------------
+
+page *cursor_page(bolt_cursor *c, pgid id);
+
+void cursor_first_leaf(bolt_cursor *c);
+
+void cursor_key_value(bolt_cursor *c, bolt_val *key, bolt_val *value, uint32_t *flags);
+
 
-// private functions
+//------------------------------------------------------------------------------
+// Public Functions
+//------------------------------------------------------------------------------
+
+// Initializes a cursor.
+void bolt_cursor_init(bolt_cursor *c, void *data, size_t pgsz, pgid root) {
+	c->data = data;
+	c->root = root;
+	c->pgsz = pgsz;
+}
+
+// Positions the cursor to the first leaf element and returns the key/value pair.
+void bolt_cursor_first(bolt_cursor *c, bolt_val *key, bolt_val *value, uint32_t *flags) {
+	// reset stack to initial state
+	c->top = 0;
+	elem_ref *ref = &(c->stack[c->top]);
+	ref->page = cursor_page(c, c->root);
+	ref->index = 0;
+
+	// Find first leaf and return key/value.
+	cursor_first_leaf(c);
+	cursor_key_value(c, key, value, flags);
+}
+
+// Positions the cursor to the next leaf element and returns the key/value pair.
+void bolt_cursor_next(bolt_cursor *c, bolt_val *key, bolt_val *value, uint32_t *flags) {
+	// Attempt to move over one element until we're successful.
+	// Move up the stack as we hit the end of each page in our stack.
+	for (int i = c->top; i >= 0; i--) {
+		elem_ref *elem = &c->stack[i];
+		if (elem->index < elem->page->count - 1) {
+			elem->index++;
+			break;
+		}
+		c->top--;
+	}
+
+	// If we are at the top of the stack then return a blank key/value pair.
+	if (c->top == -1) {
+		key->size = value->size = 0;
+		key->data = value->data = NULL;
+		*flags = 0;
+		return;
+	}
+
+	// Find first leaf and return key/value.
+	cursor_first_leaf(c);
+	cursor_key_value(c, key, value, flags);
+}
+
+
+//------------------------------------------------------------------------------
+// Private Functions
+//------------------------------------------------------------------------------
 
 // Returns a page pointer from a page identifier.
-page *get_page(bolt_cursor *c, pgid id) {
+page *cursor_page(bolt_cursor *c, pgid id) {
 	return (page *)(c->data + (c->pgsz * id));
 }
 
 // Returns the leaf element at a given index on a given page.
-branch_elem *branch_page_element(page *p, uint16_t index) {
-	branch_elem *elements = (branch_elem*)((void*)(p) + sizeof(page));
+branch_element *branch_page_element(page *p, uint16_t index) {
+	branch_element *elements = (branch_element*)((void*)(p) + sizeof(page));
 	return &elements[index];
 }
 
 // Returns the leaf element at a given index on a given page.
-leaf_elem *leaf_page_element(page *p, uint16_t index) {
-	leaf_elem *elements = (leaf_elem*)((void*)(p) + sizeof(page));
+leaf_element *page_leaf_element(page *p, uint16_t index) {
+	leaf_element *elements = (leaf_element*)((void*)(p) + sizeof(page));
 	return &elements[index];
 }
 
-// Sets the key and value for a leaf element to a bolt value.
-void key_value(leaf_elem *leaf, bolt_val *key, bolt_val *value) {
-	key->size = leaf->ksize;
-	key->data = ((void*)leaf) + leaf->pos;
-	value->size = leaf->vsize;
+// Returns the key/value pair for the current position of the cursor.
+void cursor_key_value(bolt_cursor *c, bolt_val *key, bolt_val *value, uint32_t *flags) {
+	elem_ref *ref = &(c->stack[c->top]);
+	leaf_element *elem = page_leaf_element(ref->page,ref->index);
+
+	// Assign key pointer.
+	key->size = elem->ksize;
+	key->data = ((void*)elem) + elem->pos;
+
+	// Assign value pointer.
+	value->size = elem->vsize;
 	value->data = key->data + key->size;
+
+	// Return the element flags.
+	*flags = elem->flags;
 }
 
 // Traverses from the current stack position down to the first leaf element.
-int bolt_cursor_first_leaf(bolt_cursor *c, bolt_val *key, bolt_val *value) {
-	elem_ref *ref = &(c->stack[c->stackp]);
-	branch_elem *branch;
-	while (ref->page->flags & BRANCH_PAGE) {
+void cursor_first_leaf(bolt_cursor *c) {
+	elem_ref *ref = &(c->stack[c->top]);
+	branch_element *branch;
+	while (ref->page->flags & PAGE_BRANCH) {
 		branch = branch_page_element(ref->page,ref->index);
-		c->stackp++;
-		ref = &c->stack[c->stackp];
+		c->top++;
+		ref = &c->stack[c->top];
 		ref->index = 0;
-		ref->page = get_page(c, branch->page);
+		ref->page = cursor_page(c, branch->page);
 	};
-	key_value(leaf_page_element(ref->page,ref->index), key, value);
-	return 0;
 }
 
-// public functions
-
-void bolt_cursor_init(bolt_cursor *c, void *data, size_t pgsz, pgid root) {
-	c->data = data;
-	c->root = root;
-	c->pgsz = pgsz;
-}
-
-int bolt_cursor_first(bolt_cursor *c, bolt_val *key, bolt_val *value) {
-	leaf_elem	*leaf;
-	elem_ref	*ref;
-
-	// reset stack to initial state
-	c->stackp = 0;
-	ref = &(c->stack[c->stackp]);
-	ref->page = get_page(c, c->root);
-	ref->index = 0;
-
-	// get current leaf element
-	return bolt_cursor_first_leaf(c, key, value);
-}
-
-int bolt_cursor_next(bolt_cursor *c, bolt_val *key, bolt_val *value) {
-	elem_ref *ref = &c->stack[c->stackp];
-
-	// increment element index
-	ref->index++;
-	// if we're past last element pop the stack and repeat
-	while (ref->index >= ref->page->count ) {
-		c->stackp--;
-		ref = &c->stack[c->stackp];
-		ref->index++;
-	};
-
-	// get current leaf element
-	return bolt_cursor_first_leaf(c, key, value);
-}
 */
 import "C"
 
@@ -162,19 +215,21 @@ func NewCursor(b *bolt.Bucket) *Cursor {
 	return c
 }
 
-// first moves the cursor to the first element and returns the key and value.
+// Next moves the cursor to the first element and returns the key and value.
 // Returns a nil key if there are no elements.
-func first(c *Cursor) (key, value []byte) {
+func (c *Cursor) First() (key, value []byte) {
 	var k, v C.bolt_val
-	C.bolt_cursor_first(c.C, &k, &v)
+	var flags C.uint32_t
+	C.bolt_cursor_first(c.C, &k, &v, &flags)
 	return C.GoBytes(k.data, C.int(k.size)), C.GoBytes(v.data, C.int(v.size))
 }
 
-// next moves the cursor to the next element and returns the key and value.
-// Returns a nil key if at the end of the bucket.
-func next(c *Cursor) (key, value []byte) {
+// Next moves the cursor to the next element and returns the key and value.
+// Returns a nil key if there are no more key/value pairs.
+func (c *Cursor) Next() (key, value []byte) {
 	var k, v C.bolt_val
-	C.bolt_cursor_next(c.C, &k, &v)
+	var flags C.uint32_t
+	C.bolt_cursor_next(c.C, &k, &v, &flags)
 	return C.GoBytes(k.data, C.int(k.size)), C.GoBytes(v.data, C.int(v.size))
 }
 
diff --git a/c/cursor_test.go b/c/cursor_test.go
index 3ac621f..fd0fa1a 100644
--- a/c/cursor_test.go
+++ b/c/cursor_test.go
@@ -1,123 +1,107 @@
-package c
+package c_test
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
-	// "sort"
 	"testing"
-	// "testing/quick"
 
 	"github.com/boltdb/bolt"
+	. "github.com/boltdb/bolt/c"
 	"github.com/stretchr/testify/assert"
 )
 
-// Test when cursor hits the end
-// Implement seek; binary search within the page (branch page and element page)
-
-// Ensure that a cursor can iterate over all elements in a bucket.
-// func TestIterate(t *testing.T) {
-// 	if testing.Short() {
-// 		t.Skip("skipping test in short mode.")
-// 	}
-
-// 	f := func(items testdata) bool {
-// 		withOpenDB(func(db *bolt.DB, path string) {
-// 			// Bulk insert all values.
-// 			tx, _ := db.Begin(true)
-// 			tx.CreateBucket("widgets")
-// 			b := tx.Bucket("widgets")
-// 			for _, item := range items {
-// 				assert.NoError(t, b.Put(item.Key, item.Value))
-// 			}
-// 			assert.NoError(t, tx.Commit())
-
-// 			// Sort test data.
-// 			sort.Sort(items)
-
-// 			// Iterate over all items and check consistency.
-// 			var index = 0
-// 			tx, _ = db.Begin(false)
-// 			c := NewCursor(tx.Bucket("widgets"))
-// 			for key, value := first(c); key != nil && index < len(items); key, value = next(c) {
-// 				assert.Equal(t, key, items[index].Key)
-// 				assert.Equal(t, value, items[index].Value)
-// 				index++
-// 			}
-// 			assert.Equal(t, len(items), index)
-// 			assert.Equal(t, len(items), index)
-// 			tx.Rollback()
-// 		})
-// 		return true
-// 	}
-// 	if err := quick.Check(f, qconfig()); err != nil {
-// 		t.Error(err)
-// 	}
-// 	fmt.Fprint(os.Stderr, "\n")
-// }
-
-func TestCursorFirst(t *testing.T) {
-	withOpenDB(func(db *bolt.DB, path string) {
-
-		// Bulk insert all values.
-		tx, _ := db.Begin(true)
-		b, _ := tx.CreateBucket([]byte("widgets"))
-		assert.NoError(t, b.Put([]byte("foo"), []byte("barz")))
-		assert.NoError(t, tx.Commit())
-
-		// Get first and check consistency
-		tx, _ = db.Begin(false)
-		c := NewCursor(tx.Bucket([]byte("widgets")))
-		key, value := first(c)
-		assert.Equal(t, key, []byte("foo"))
-		assert.Equal(t, value, []byte("barz"))
+// Ensure that the C cursor can
+func TestCursor_First(t *testing.T) {
+	withDB(func(db *bolt.DB) {
+		db.Update(func(tx *bolt.Tx) error {
+			b, _ := tx.CreateBucket([]byte("widgets"))
+			return b.Put([]byte("foo"), []byte("barz"))
+		})
+		db.View(func(tx *bolt.Tx) error {
+			c := NewCursor(tx.Bucket([]byte("widgets")))
+			key, value := c.First()
+			assert.Equal(t, []byte("foo"), key)
+			assert.Equal(t, []byte("barz"), value)
+			return nil
+		})
+	})
+}
 
-		tx.Rollback()
+// Ensure that a C cursor can iterate over a single root with a couple elements.
+func TestCursor_Iterate_Leaf(t *testing.T) {
+	withDB(func(db *bolt.DB) {
+		db.Update(func(tx *bolt.Tx) error {
+			tx.CreateBucket([]byte("widgets"))
+			tx.Bucket([]byte("widgets")).Put([]byte("baz"), []byte{})
+			tx.Bucket([]byte("widgets")).Put([]byte("foo"), []byte{0})
+			tx.Bucket([]byte("widgets")).Put([]byte("bar"), []byte{1})
+			return nil
+		})
+		db.View(func(tx *bolt.Tx) error {
+			c := NewCursor(tx.Bucket([]byte("widgets")))
+
+			k, v := c.First()
+			assert.Equal(t, string(k), "bar")
+			assert.Equal(t, []byte{1}, v)
+
+			k, v = c.Next()
+			assert.Equal(t, string(k), "baz")
+			assert.Equal(t, []byte{}, v)
+
+			k, v = c.Next()
+			assert.Equal(t, string(k), "foo")
+			assert.Equal(t, []byte{0}, v)
+
+			k, v = c.Next()
+			assert.Equal(t, []byte{}, k)
+			assert.Equal(t, []byte{}, v)
+
+			k, v = c.Next()
+			assert.Equal(t, []byte{}, k)
+			assert.Equal(t, []byte{}, v)
+			return nil
+		})
 	})
 }
 
-// withTempPath executes a function with a database reference.
-func withTempPath(fn func(string)) {
-	f, _ := ioutil.TempFile("", "bolt-")
-	path := f.Name()
+// tempfile returns a temporary path.
+func tempfile() string {
+	f, _ := ioutil.TempFile("", "bolt-c-")
 	f.Close()
-	os.Remove(path)
-	defer os.RemoveAll(path)
-
-	fn(path)
+	os.Remove(f.Name())
+	return f.Name()
 }
 
-// withOpenDB executes a function with an already opened database.
-func withOpenDB(fn func(*bolt.DB, string)) {
-	withTempPath(func(path string) {
-		db, err := bolt.Open(path, 0666)
-		if err != nil {
-			panic("cannot open db: " + err.Error())
-		}
-		defer db.Close()
-		fn(db, path)
+// withDB executes a function with an already opened database.
+func withDB(fn func(*bolt.DB)) {
+	path := tempfile()
+	db, err := bolt.Open(path, 0666)
+	if err != nil {
+		panic("cannot open db: " + err.Error())
+	}
+	defer os.Remove(path)
+	defer db.Close()
 
-		// Log statistics.
-		// if *statsFlag {
-		// 	logStats(db)
-		// }
+	fn(db)
 
-		// Check database consistency after every test.
-		mustCheck(db)
-	})
+	// Check database consistency after every test.
+	mustCheck(db)
 }
 
 // mustCheck runs a consistency check on the database and panics if any errors are found.
 func mustCheck(db *bolt.DB) {
 	if err := db.Check(); err != nil {
 		// Copy db off first.
-		db.CopyFile("/tmp/check.db", 0600)
+		var path = tempfile()
+		db.CopyFile(path, 0600)
 
 		if errors, ok := err.(bolt.ErrorList); ok {
 			for _, err := range errors {
-				warn(err)
+				fmt.Println(err)
 			}
 		}
-		warn(err)
-		panic("check failure: see /tmp/check.db")
+		fmt.Println(err)
+		panic("check failure: " + path)
 	}
 }
diff --git a/c/doc.go b/c/doc.go
new file mode 100644
index 0000000..cbb98fe
--- /dev/null
+++ b/c/doc.go
@@ -0,0 +1,4 @@
+/*
+Package c provides a C interface to Bolt.
+*/
+package c
diff --git a/c/quick_test.go b/c/quick_test.go
deleted file mode 100644
index 7d87249..0000000
--- a/c/quick_test.go
+++ /dev/null
@@ -1,77 +0,0 @@
-package c
-
-import (
-	"bytes"
-	"flag"
-	"math/rand"
-	"reflect"
-	"testing/quick"
-	"time"
-)
-
-// testing/quick defaults to 5 iterations and a random seed.
-// You can override these settings from the command line:
-//
-//   -quick.count     The number of iterations to perform.
-//   -quick.seed      The seed to use for randomizing.
-//   -quick.maxitems  The maximum number of items to insert into a DB.
-//   -quick.maxksize  The maximum size of a key.
-//   -quick.maxvsize  The maximum size of a value.
-//
-
-var qcount, qseed, qmaxitems, qmaxksize, qmaxvsize int
-
-func init() {
-	flag.IntVar(&qcount, "quick.count", 5, "")
-	flag.IntVar(&qseed, "quick.seed", int(time.Now().UnixNano())%100000, "")
-	flag.IntVar(&qmaxitems, "quick.maxitems", 1000, "")
-	flag.IntVar(&qmaxksize, "quick.maxksize", 1024, "")
-	flag.IntVar(&qmaxvsize, "quick.maxvsize", 1024, "")
-	flag.Parse()
-	warn("seed:", qseed)
-	warnf("quick settings: count=%v, items=%v, ksize=%v, vsize=%v", qcount, qmaxitems, qmaxksize, qmaxvsize)
-}
-
-func qconfig() *quick.Config {
-	return &quick.Config{
-		MaxCount: qcount,
-		Rand:     rand.New(rand.NewSource(int64(qseed))),
-	}
-}
-
-type testdata []testdataitem
-
-func (t testdata) Len() int           { return len(t) }
-func (t testdata) Swap(i, j int)      { t[i], t[j] = t[j], t[i] }
-func (t testdata) Less(i, j int) bool { return bytes.Compare(t[i].Key, t[j].Key) == -1 }
-
-func (t testdata) Generate(rand *rand.Rand, size int) reflect.Value {
-	n := rand.Intn(qmaxitems-1) + 1
-	items := make(testdata, n)
-	for i := 0; i < n; i++ {
-		item := &items[i]
-		item.Key = randByteSlice(rand, 1, qmaxksize)
-		item.Value = randByteSlice(rand, 0, qmaxvsize)
-	}
-	return reflect.ValueOf(items)
-}
-
-type revtestdata []testdataitem
-
-func (t revtestdata) Len() int           { return len(t) }
-func (t revtestdata) Swap(i, j int)      { t[i], t[j] = t[j], t[i] }
-func (t revtestdata) Less(i, j int) bool { return bytes.Compare(t[i].Key, t[j].Key) == 1 }
-
-type testdataitem struct {
-	Key   []byte
-	Value []byte
-}
-
-func randByteSlice(rand *rand.Rand, minSize, maxSize int) []byte {
-	n := rand.Intn(maxSize-minSize) + minSize
-	b := make([]byte, n)
-	for i := 0; i < n; i++ {
-		b[i] = byte(rand.Intn(255))
-	}
-	return b
-}