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Philip Stutz
committed
Cursors get their own key and value buffers
This allows to concurrently use the same read transaction with multiple cursors (related to conversation in #35).
1 parent 2b2f239 commit 2132503

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5 files changed

+107
-60
lines changed

5 files changed

+107
-60
lines changed

‎src/main/java/org/lmdbjava/Cursor.java‎

Lines changed: 71 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -23,9 +23,12 @@
2323
import static java.util.Objects.requireNonNull;
2424
import jnr.ffi.Pointer;
2525
import jnr.ffi.byref.NativeLongByReference;
26+
import jnr.ffi.provider.MemoryManager;
27+
import static org.lmdbjava.BufferProxy.MDB_VAL_STRUCT_SIZE;
2628
import static org.lmdbjava.Dbi.KeyNotFoundException.MDB_NOTFOUND;
2729
import static org.lmdbjava.Env.SHOULD_CHECK;
2830
import static org.lmdbjava.Library.LIB;
31+
import static org.lmdbjava.Library.RUNTIME;
2932
import static org.lmdbjava.MaskedFlag.mask;
3033
import static org.lmdbjava.PutFlags.MDB_RESERVE;
3134
import static org.lmdbjava.ResultCodeMapper.checkRc;
@@ -41,15 +44,62 @@
4144
*/
4245
public final class Cursor<T> implements AutoCloseable {
4346

47+
private static final MemoryManager MEM_MGR = RUNTIME.getMemoryManager();
4448
private boolean closed;
4549
private final Pointer ptrCursor;
4650
private Txn<T> txn;
4751

52+
private T k;
53+
private final BufferProxy<T> proxy;
54+
private final Pointer ptrKey;
55+
private final long ptrKeyAddr;
56+
private final Pointer ptrVal;
57+
private final long ptrValAddr;
58+
private T v;
59+
4860
Cursor(final Pointer ptr, final Txn<T> txn) {
4961
requireNonNull(ptr);
5062
requireNonNull(txn);
5163
this.ptrCursor = ptr;
5264
this.txn = txn;
65+
66+
this.proxy = txn.proxy;
67+
this.k = proxy.allocate();
68+
this.v = proxy.allocate();
69+
ptrKey = MEM_MGR.allocateTemporary(MDB_VAL_STRUCT_SIZE, false);
70+
ptrKeyAddr = ptrKey.address();
71+
ptrVal = MEM_MGR.allocateTemporary(MDB_VAL_STRUCT_SIZE, false);
72+
ptrValAddr = ptrVal.address();
73+
}
74+
75+
void keyIn(final T key) {
76+
proxy.in(key, ptrKey, ptrKeyAddr);
77+
}
78+
79+
T keyOut() {
80+
k = proxy.out(k, ptrKey, ptrKeyAddr);
81+
return k;
82+
}
83+
84+
Pointer pointerKey() {
85+
return ptrKey;
86+
}
87+
88+
Pointer pointerVal() {
89+
return ptrVal;
90+
}
91+
92+
void valIn(final T val) {
93+
proxy.in(val, ptrVal, ptrValAddr);
94+
}
95+
96+
void valIn(final int size) {
97+
proxy.in(v, size, ptrVal, ptrValAddr);
98+
}
99+
100+
T valOut() {
101+
v = proxy.out(v, ptrVal, ptrValAddr);
102+
return v;
53103
}
54104

55105
/**
@@ -68,6 +118,8 @@ public void close() {
68118
txn.checkReady();
69119
}
70120
LIB.mdb_cursor_close(ptrCursor);
121+
proxy.deallocate(k);
122+
proxy.deallocate(v);
71123
closed = true;
72124
}
73125

@@ -131,26 +183,25 @@ public boolean get(final T key, final GetOp op) {
131183
checkNotClosed();
132184
txn.checkReady();
133185
}
134-
txn.keyIn(key);
186+
keyIn(key);
135187

136-
final int rc = LIB.mdb_cursor_get(ptrCursor, txn.pointerKey(), txn.
137-
pointerVal(), op.getCode());
188+
final int rc = LIB.mdb_cursor_get(ptrCursor, pointerKey(), pointerVal(), op.getCode());
138189

139190
if (rc == MDB_NOTFOUND) {
140191
return false;
141192
}
142193

143194
checkRc(rc);
144-
txn.keyOut();
145-
txn.valOut();
195+
keyOut();
196+
valOut();
146197
return true;
147198
}
148199

149200
/**
150201
* @return the key that the cursor is located at.
151202
*/
152203
public T key() {
153-
return txn.key();
204+
return k;
154205
}
155206

156207
/**
@@ -199,13 +250,12 @@ public void put(final T key, final T val, final PutFlags... op) {
199250
txn.checkReady();
200251
txn.checkWritesAllowed();
201252
}
202-
txn.keyIn(key);
203-
txn.valIn(val);
253+
keyIn(key);
254+
valIn(val);
204255
final int flags = mask(op);
205-
checkRc(LIB.mdb_cursor_put(ptrCursor, txn.pointerKey(), txn.pointerVal(),
206-
flags));
207-
txn.keyOut();
208-
txn.valOut();
256+
checkRc(LIB.mdb_cursor_put(ptrCursor, pointerKey(), pointerVal(), flags));
257+
keyOut();
258+
valOut();
209259
}
210260

211261
/**
@@ -256,13 +306,12 @@ public T reserve(final T key, final int size, final PutFlags... op) {
256306
txn.checkReady();
257307
txn.checkWritesAllowed();
258308
}
259-
txn.keyIn(key);
260-
txn.valIn(size);
309+
keyIn(key);
310+
valIn(size);
261311
final int flags = mask(op) | MDB_RESERVE.getMask();
262-
checkRc(LIB.mdb_cursor_put(ptrCursor, txn.pointerKey(), txn.pointerVal(),
263-
flags));
264-
txn.valOut();
265-
return txn.val();
312+
checkRc(LIB.mdb_cursor_put(ptrCursor, pointerKey(), pointerVal(), flags));
313+
valOut();
314+
return val();
266315
}
267316

268317
/**
@@ -278,25 +327,23 @@ public boolean seek(final SeekOp op) {
278327
txn.checkReady();
279328
}
280329

281-
final int rc = LIB.mdb_cursor_get(ptrCursor, txn.pointerKey(), txn.
282-
pointerVal(),
283-
op.getCode());
330+
final int rc = LIB.mdb_cursor_get(ptrCursor, pointerKey(), pointerVal(), op.getCode());
284331

285332
if (rc == MDB_NOTFOUND) {
286333
return false;
287334
}
288335

289336
checkRc(rc);
290-
txn.keyOut();
291-
txn.valOut();
337+
keyOut();
338+
valOut();
292339
return true;
293340
}
294341

295342
/**
296343
* @return the value that the cursor is located at.
297344
*/
298345
public T val() {
299-
return txn.val();
346+
return v;
300347
}
301348

302349
private void checkNotClosed() throws ClosedException {

‎src/main/java/org/lmdbjava/Txn.java‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -44,9 +44,9 @@
4444
public final class Txn<T> implements AutoCloseable {
4545

4646
private static final MemoryManager MEM_MGR = RUNTIME.getMemoryManager();
47+
final BufferProxy<T> proxy;
4748
private T k;
4849
private final Txn<T> parent;
49-
private final BufferProxy<T> proxy;
5050
private final Pointer ptr;
5151
private final Pointer ptrKey;
5252
private final long ptrKeyAddr;

‎src/test/java/org/lmdbjava/CursorParamTest.java‎

Lines changed: 12 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -121,33 +121,33 @@ public final void execute(final TemporaryFolder tmp) {
121121
// check MDB_SET operations
122122
final T key3 = set(3);
123123
assertThat(c.get(key3, MDB_SET_KEY), is(true));
124-
assertThat(get(txn.key()), is(3));
125-
assertThat(get(txn.val()), is(4));
124+
assertThat(get(c.key()), is(3));
125+
assertThat(get(c.val()), is(4));
126126
final T key6 = set(6);
127127
assertThat(c.get(key6, MDB_SET_RANGE), is(true));
128-
assertThat(get(txn.key()), is(7));
128+
assertThat(get(c.key()), is(7));
129129
if (!(this instanceof ByteArrayRunner)) {
130-
assertThat(get(txn.val()), is(8));
130+
assertThat(get(c.val()), is(8));
131131
}
132132
final T key999 = set(999);
133133
assertThat(c.get(key999, MDB_SET_KEY), is(false));
134134

135135
// check MDB navigation operations
136136
assertThat(c.seek(MDB_LAST), is(true));
137-
final int mdb1 = get(txn.key());
138-
final int mdb2 = get(txn.val());
137+
final int mdb1 = get(c.key());
138+
final int mdb2 = get(c.val());
139139

140140
assertThat(c.seek(MDB_PREV), is(true));
141-
final int mdb3 = get(txn.key());
142-
final int mdb4 = get(txn.val());
141+
final int mdb3 = get(c.key());
142+
final int mdb4 = get(c.val());
143143

144144
assertThat(c.seek(MDB_NEXT), is(true));
145-
final int mdb5 = get(txn.key());
146-
final int mdb6 = get(txn.val());
145+
final int mdb5 = get(c.key());
146+
final int mdb6 = get(c.val());
147147

148148
assertThat(c.seek(MDB_FIRST), is(true));
149-
final int mdb7 = get(txn.key());
150-
final int mdb8 = get(txn.val());
149+
final int mdb7 = get(c.key());
150+
final int mdb8 = get(c.val());
151151

152152
// assert afterwards to ensure memory address from LMDB
153153
// are valid within same txn and across cursor movement

‎src/test/java/org/lmdbjava/CursorTest.java‎

Lines changed: 12 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -131,21 +131,21 @@ public void cursorFirstLastNextPrev() {
131131
c.put(bb(7), bb(8));
132132

133133
assertThat(c.first(), is(true));
134-
assertThat(txn.key().getInt(0), is(1));
135-
assertThat(txn.val().getInt(0), is(2));
134+
assertThat(c.key().getInt(0), is(1));
135+
assertThat(c.val().getInt(0), is(2));
136136

137137
assertThat(c.last(), is(true));
138-
assertThat(txn.key().getInt(0), is(7));
139-
assertThat(txn.val().getInt(0), is(8));
138+
assertThat(c.key().getInt(0), is(7));
139+
assertThat(c.val().getInt(0), is(8));
140140

141141
assertThat(c.prev(), is(true));
142-
assertThat(txn.key().getInt(0), is(5));
143-
assertThat(txn.val().getInt(0), is(6));
142+
assertThat(c.key().getInt(0), is(5));
143+
assertThat(c.val().getInt(0), is(6));
144144

145145
assertThat(c.first(), is(true));
146146
assertThat(c.next(), is(true));
147-
assertThat(txn.key().getInt(0), is(3));
148-
assertThat(txn.val().getInt(0), is(4));
147+
assertThat(c.key().getInt(0), is(3));
148+
assertThat(c.val().getInt(0), is(4));
149149
}
150150
}
151151

@@ -157,12 +157,12 @@ public void delete() {
157157
c.put(bb(1), bb(2), MDB_NOOVERWRITE);
158158
c.put(bb(3), bb(4));
159159
assertThat(c.seek(MDB_FIRST), is(true));
160-
assertThat(txn.key().getInt(), is(1));
161-
assertThat(txn.val().getInt(), is(2));
160+
assertThat(c.key().getInt(), is(1));
161+
assertThat(c.val().getInt(), is(2));
162162
c.delete();
163163
assertThat(c.seek(MDB_FIRST), is(true));
164-
assertThat(txn.key().getInt(), is(3));
165-
assertThat(txn.val().getInt(), is(4));
164+
assertThat(c.key().getInt(), is(3));
165+
assertThat(c.val().getInt(), is(4));
166166
c.delete();
167167
assertThat(c.seek(MDB_FIRST), is(false));
168168
}

‎src/test/java/org/lmdbjava/TutorialTest.java‎

Lines changed: 11 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -252,17 +252,17 @@ public void tutorial3() throws IOException {
252252

253253
// We can read from the Cursor by key.
254254
c.get(key, MDB_SET);
255-
assertThat(UTF_8.decode(txn.key()).toString(), is("ccc"));
255+
assertThat(UTF_8.decode(c.key()).toString(), is("ccc"));
256256

257257
// Let's see that LMDB provides the keys in appropriate order....
258258
c.seek(MDB_FIRST);
259-
assertThat(UTF_8.decode(txn.key()).toString(), is("aaa"));
259+
assertThat(UTF_8.decode(c.key()).toString(), is("aaa"));
260260

261261
c.seek(MDB_LAST);
262-
assertThat(UTF_8.decode(txn.key()).toString(), is("zzz"));
262+
assertThat(UTF_8.decode(c.key()).toString(), is("zzz"));
263263

264264
c.seek(MDB_PREV);
265-
assertThat(UTF_8.decode(txn.key()).toString(), is("ccc"));
265+
assertThat(UTF_8.decode(c.key()).toString(), is("ccc"));
266266

267267
// Cursors can also delete the current key.
268268
c.delete();
@@ -388,13 +388,13 @@ public void tutorial5() throws IOException {
388388

389389
// Let's position the Cursor. Note sorting still works.
390390
c.seek(MDB_FIRST);
391-
assertThat(UTF_8.decode(txn.val()).toString(), is("kkk"));
391+
assertThat(UTF_8.decode(c.val()).toString(), is("kkk"));
392392

393393
c.seek(MDB_LAST);
394-
assertThat(UTF_8.decode(txn.val()).toString(), is("xxx"));
394+
assertThat(UTF_8.decode(c.val()).toString(), is("xxx"));
395395

396396
c.seek(MDB_PREV);
397-
assertThat(UTF_8.decode(txn.val()).toString(), is("lll"));
397+
assertThat(UTF_8.decode(c.val()).toString(), is("lll"));
398398

399399
c.close();
400400
txn.commit();
@@ -436,11 +436,11 @@ public void tutorial6() throws IOException {
436436
c.put(key, val);
437437

438438
c.seek(MDB_FIRST);
439-
assertThat(txn.key().getStringWithoutLengthUtf8(0, env.getMaxKeySize()),
439+
assertThat(c.key().getStringWithoutLengthUtf8(0, env.getMaxKeySize()),
440440
startsWith("ggg"));
441441

442442
c.seek(MDB_LAST);
443-
assertThat(txn.key().getStringWithoutLengthUtf8(0, env.getMaxKeySize()),
443+
assertThat(c.key().getStringWithoutLengthUtf8(0, env.getMaxKeySize()),
444444
startsWith("yyy"));
445445

446446
// DirectBuffer has no notion of a position. Often you don't want to store
@@ -454,8 +454,8 @@ public void tutorial6() throws IOException {
454454
assertThat(key.capacity(), is(keyLen));
455455
c.put(key, val);
456456
c.seek(MDB_FIRST);
457-
assertThat(txn.key().capacity(), is(keyLen));
458-
assertThat(txn.key().getStringWithoutLengthUtf8(0, txn.key().capacity()),
457+
assertThat(c.key().capacity(), is(keyLen));
458+
assertThat(c.key().getStringWithoutLengthUtf8(0, c.key().capacity()),
459459
is("12characters"));
460460

461461
// If we want to store bigger values again, just wrap our original buffer.

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