Wrap the interruption to a custom exception when a blocking API is interrupted (#99)

### Motivation

Currently, when a blocking API is interrupted by a signal, `SystemError`
will be thrown. However, in this case, `PyErr_SetInterrupt` will be
called and next time a blocking API is called, `std::system_error` will
be somehow thrown.

The failure of
https://lists.apache.org/thread/cmzykd9qz9x1d0s35nc5912o3slwpxpv is
caused by this issue. The `SystemError` is not called, then
`client.close()` will be skipped, which leads to the `bad_weak_ptr`
error.

P.S. Currently we have to call `client.close()` on a `Client` instance,
otherwise, the `bad_weak_ptr` will be thrown.

However, even if we caught the `SystemError` like:

```python
    try:
        msg = consumer.receive()
        # ...
    except SystemError:
        break
```

we would still see the following error:

```
terminate called after throwing an instance of 'std::system_error'
  what():  Operation not permitted
Aborted
```

### Modifications

- Wrap `ResultInterrupted` into the `pulsar.Interrupted` exception.
- Refactor the `waitForAsyncValue` and `waitForAsyncResult` functions
  and raise `pulsar.Interrupted` when `PyErr_CheckSignals` detects a
  signal.
- Add `InterruptedTest` to cover this case.
- Remove `future.h` since we now use `std::future` instead of the
  manually implemented `Future`.
- Fix the `examples/consumer.py` to support stopping by Ctrl+C.

(cherry picked from commit ec05f50)

Author: BewareMyPower

examples/consumer.py

@@ -29,8 +29,12 @@
                             })
 
 while True:
-    msg = consumer.receive()
-    print("Received message '{0}' id='{1}'".format(msg.data().decode('utf-8'), msg.message_id()))
-    consumer.acknowledge(msg)
+    try:
+        msg = consumer.receive()
+        print("Received message '{0}' id='{1}'".format(msg.data().decode('utf-8'), msg.message_id()))
+        consumer.acknowledge(msg)
+    except pulsar.Interrupted:
+        print("Stop receiving messages")
+        break
 
 client.close()

pulsar/exceptions.py

@@ -25,4 +25,4 @@
     ProducerBlockedQuotaExceededException, ProducerQueueIsFull, MessageTooBig, TopicNotFound, SubscriptionNotFound, \
     ConsumerNotFound, UnsupportedVersionError, TopicTerminated, CryptoError, IncompatibleSchema, ConsumerAssignError, \
     CumulativeAcknowledgementNotAllowedError, TransactionCoordinatorNotFoundError, InvalidTxnStatusError, \
-    NotAllowedError, TransactionConflict, TransactionNotFound, ProducerFenced, MemoryBufferIsFull
+    NotAllowedError, TransactionConflict, TransactionNotFound, ProducerFenced, MemoryBufferIsFull, Interrupted

src/client.cc

@@ -24,73 +24,38 @@
 namespace py = pybind11;
 
 Producer Client_createProducer(Client& client, const std::string& topic, const ProducerConfiguration& conf) {
-    Producer producer;
-
-    waitForAsyncValue(std::function<void(CreateProducerCallback)>([&](CreateProducerCallback callback) {
-                          client.createProducerAsync(topic, conf, callback);
-                      }),
-                      producer);
-
-    return producer;
+    return waitForAsyncValue<Producer>(
+        [&](CreateProducerCallback callback) { client.createProducerAsync(topic, conf, callback); });
 }
 
 Consumer Client_subscribe(Client& client, const std::string& topic, const std::string& subscriptionName,
                           const ConsumerConfiguration& conf) {
-    Consumer consumer;
-
-    waitForAsyncValue(std::function<void(SubscribeCallback)>([&](SubscribeCallback callback) {
-                          client.subscribeAsync(topic, subscriptionName, conf, callback);
-                      }),
-                      consumer);
-
-    return consumer;
+    return waitForAsyncValue<Consumer>(
+        [&](SubscribeCallback callback) { client.subscribeAsync(topic, subscriptionName, conf, callback); });
 }
 
 Consumer Client_subscribe_topics(Client& client, const std::vector<std::string>& topics,
                                  const std::string& subscriptionName, const ConsumerConfiguration& conf) {
-    Consumer consumer;
-
-    waitForAsyncValue(std::function<void(SubscribeCallback)>([&](SubscribeCallback callback) {
-                          client.subscribeAsync(topics, subscriptionName, conf, callback);
-                      }),
-                      consumer);
-
-    return consumer;
+    return waitForAsyncValue<Consumer>(
+        [&](SubscribeCallback callback) { client.subscribeAsync(topics, subscriptionName, conf, callback); });
 }
 
 Consumer Client_subscribe_pattern(Client& client, const std::string& topic_pattern,
                                   const std::string& subscriptionName, const ConsumerConfiguration& conf) {
-    Consumer consumer;
-
-    waitForAsyncValue(std::function<void(SubscribeCallback)>([&](SubscribeCallback callback) {
-                          client.subscribeWithRegexAsync(topic_pattern, subscriptionName, conf, callback);
-                      }),
-                      consumer);
-
-    return consumer;
+    return waitForAsyncValue<Consumer>([&](SubscribeCallback callback) {
+        client.subscribeWithRegexAsync(topic_pattern, subscriptionName, conf, callback);
+    });
 }
 
 Reader Client_createReader(Client& client, const std::string& topic, const MessageId& startMessageId,
                            const ReaderConfiguration& conf) {
-    Reader reader;
-
-    waitForAsyncValue(std::function<void(ReaderCallback)>([&](ReaderCallback callback) {
-                          client.createReaderAsync(topic, startMessageId, conf, callback);
-                      }),
-                      reader);
-
-    return reader;
+    return waitForAsyncValue<Reader>(
+        [&](ReaderCallback callback) { client.createReaderAsync(topic, startMessageId, conf, callback); });
 }
 
 std::vector<std::string> Client_getTopicPartitions(Client& client, const std::string& topic) {
-    std::vector<std::string> partitions;
-
-    waitForAsyncValue(std::function<void(GetPartitionsCallback)>([&](GetPartitionsCallback callback) {
-                          client.getPartitionsForTopicAsync(topic, callback);
-                      }),
-                      partitions);
-
-    return partitions;
+    return waitForAsyncValue<std::vector<std::string>>(
+        [&](GetPartitionsCallback callback) { client.getPartitionsForTopicAsync(topic, callback); });
 }
 
 void Client_close(Client& client) {

src/consumer.cc

@@ -29,13 +29,7 @@ void Consumer_unsubscribe(Consumer& consumer) {
 }
 
 Message Consumer_receive(Consumer& consumer) {
-    Message msg;
-
-    waitForAsyncValue(std::function<void(ReceiveCallback)>(
-                          [&consumer](ReceiveCallback callback) { consumer.receiveAsync(callback); }),
-                      msg);
-
-    return msg;
+    return waitForAsyncValue<Message>([&](ReceiveCallback callback) { consumer.receiveAsync(callback); });
 }
 
 Message Consumer_receive_timeout(Consumer& consumer, int timeoutMs) {
@@ -59,32 +53,27 @@ Messages Consumer_batch_receive(Consumer& consumer) {
 void Consumer_acknowledge(Consumer& consumer, const Message& msg) { consumer.acknowledgeAsync(msg, nullptr); }
 
 void Consumer_acknowledge_message_id(Consumer& consumer, const MessageId& msgId) {
-    Py_BEGIN_ALLOW_THREADS
-    consumer.acknowledgeAsync(msgId, nullptr);
+    Py_BEGIN_ALLOW_THREADS consumer.acknowledgeAsync(msgId, nullptr);
     Py_END_ALLOW_THREADS
 }
 
 void Consumer_negative_acknowledge(Consumer& consumer, const Message& msg) {
-    Py_BEGIN_ALLOW_THREADS
-    consumer.negativeAcknowledge(msg);
+    Py_BEGIN_ALLOW_THREADS consumer.negativeAcknowledge(msg);
     Py_END_ALLOW_THREADS
 }
 
 void Consumer_negative_acknowledge_message_id(Consumer& consumer, const MessageId& msgId) {
-    Py_BEGIN_ALLOW_THREADS
-    consumer.negativeAcknowledge(msgId);
+    Py_BEGIN_ALLOW_THREADS consumer.negativeAcknowledge(msgId);
     Py_END_ALLOW_THREADS
 }
 
 void Consumer_acknowledge_cumulative(Consumer& consumer, const Message& msg) {
-    Py_BEGIN_ALLOW_THREADS
-    consumer.acknowledgeCumulativeAsync(msg, nullptr);
+    Py_BEGIN_ALLOW_THREADS consumer.acknowledgeCumulativeAsync(msg, nullptr);
     Py_END_ALLOW_THREADS
 }
 
 void Consumer_acknowledge_cumulative_message_id(Consumer& consumer, const MessageId& msgId) {
-    Py_BEGIN_ALLOW_THREADS
-    consumer.acknowledgeCumulativeAsync(msgId, nullptr);
+    Py_BEGIN_ALLOW_THREADS consumer.acknowledgeCumulativeAsync(msgId, nullptr);
     Py_END_ALLOW_THREADS
 }
 

src/future.h

@@ -25,21 +25,15 @@
 namespace py = pybind11;
 
 MessageId Producer_send(Producer& producer, const Message& message) {
-    MessageId messageId;
-
-    waitForAsyncValue(std::function<void(SendCallback)>(
-                          [&](SendCallback callback) { producer.sendAsync(message, callback); }),
-                      messageId);
-
-    return messageId;
+    return waitForAsyncValue<MessageId>(
+        [&](SendCallback callback) { producer.sendAsync(message, callback); });
 }
 
 void Producer_sendAsync(Producer& producer, const Message& msg, SendCallback callback) {
-    Py_BEGIN_ALLOW_THREADS
-    producer.sendAsync(msg, callback);
+    Py_BEGIN_ALLOW_THREADS producer.sendAsync(msg, callback);
     Py_END_ALLOW_THREADS
 
-    if (PyErr_CheckSignals() == -1) {
+        if (PyErr_CheckSignals() == -1) {
         PyErr_SetInterrupt();
     }
 }

src/producer.cc

@@ -62,14 +62,8 @@ Message Reader_readNextTimeout(Reader& reader, int timeoutMs) {
 }
 
 bool Reader_hasMessageAvailable(Reader& reader) {
-    bool available = false;
-
-    waitForAsyncValue(
-        std::function<void(HasMessageAvailableCallback)>(
-            [&](HasMessageAvailableCallback callback) { reader.hasMessageAvailableAsync(callback); }),
-        available);
-
-    return available;
+    return waitForAsyncValue<bool>(
+        [&](HasMessageAvailableCallback callback) { reader.hasMessageAvailableAsync(callback); });
 }
 
 void Reader_close(Reader& reader) {