Learning Concurrent Programming in Scala

Cover ......Page 1
Copyright......Page 3
Credits......Page 4
Foreword......Page 5
About the Author......Page 7
Acknowledgements......Page 8
About the Reviewers......Page 10
www.PacktPub.com......Page 13
Customer Feedback......Page 14
Table of Contents......Page 16
Preface......Page 21
Chapter 1: Introduction......Page 33
Concurrent programming......Page 34
Modern concurrency paradigms......Page 35
The advantages of Scala......Page 37
Execution of a Scala program......Page 38
A Scala primer......Page 40
Overview of new features in Scala 2.12......Page 45
Exercises......Page 46
Chapter 2: Concurrency on the JVM and the Java Memory Model......Page 49
Processes and threads......Page 50
Creating and starting threads......Page 53
Atomic execution......Page 58
Reordering......Page 62
Monitors and synchronization......Page 65
Deadlocks......Page 67
Guarded blocks......Page 70
Interrupting threads and the graceful shutdown......Page 75
Volatile variables......Page 76
The Java Memory Model......Page 78
Immutable objects and final fields......Page 80
Summary......Page 82
Exercises......Page 83
Chapter 3: Traditional Building Blocks of Concurrency......Page 87
The Executor and ExecutionContext objects......Page 88
Atomic primitives......Page 92
Atomic variables......Page 93
Lock-free programming......Page 96
Implementing locks explicitly......Page 98
The ABA problem......Page 100
Lazy values......Page 103
Concurrent collections......Page 108
Concurrent queues......Page 109
Concurrent sets and maps......Page 113
Concurrent traversals......Page 118
Custom concurrent data structures......Page 121
Implementing a lock-free concurrent pool......Page 122
Creating and handling processes......Page 126
Summary......Page 128
Exercises......Page 129
Chapter 4: Asynchronous Programming with Futures and Promises......Page 132
Futures......Page 133
Starting future computations......Page 135
Future callbacks......Page 137
Futures and exceptions......Page 140
Using the Try type......Page 141
Fatal exceptions......Page 143
Functional composition on futures......Page 144
Promises......Page 152
Converting callback-based APIs......Page 154
Extending the future API......Page 157
Cancellation of asynchronous computations......Page 158
Awaiting futures......Page 161
Blocking in asynchronous computations......Page 162
The Scala Async library......Page 163
Alternative future frameworks......Page 166
Exercises......Page 168
Chapter 5: Data-Parallel Collections......Page 172
Scala collections in a nutshell......Page 173
Using parallel collections......Page 174
Parallel collection class hierarchy......Page 178
Configuring the parallelism level......Page 180
Measuring the performance on the JVM......Page 181
Non-parallelizable collections......Page 184
Non-parallelizable operations......Page 185
Side effects in parallel operations......Page 188
Nondeterministic parallel operations......Page 189
Commutative and associative operators......Page 190
Using parallel and concurrent collections together......Page 193
Weakly consistent iterators......Page 194
Implementing custom parallel collections......Page 195
Splitters......Page 196
Combiners......Page 199
Summary......Page 202
Exercises......Page 204
Chapter 6: Concurrent Programming with Reactive Extensions......Page 206
Creating Observable objects......Page 208
Observables and exceptions......Page 210
The Observable contract......Page 212
Implementing custom Observable objects......Page 214
Creating Observables from futures......Page 215
Subscriptions......Page 216
Composing Observable objects......Page 219
Nested Observables......Page 221
Failure handling in Observables......Page 226
Rx schedulers......Page 229
Using custom schedulers for UI applications......Page 231
Subjects and top-down reactive programming......Page 238
Exercises......Page 243
Chapter 7: Software Transactional Memory......Page 247
The trouble with atomic variables......Page 248
Using Software Transactional Memory......Page 252
Transactional references......Page 255
Using the atomic statement......Page 256
The interaction between transactions and side effects......Page 258
Single-operation transactions......Page 263
Nesting transactions......Page 264
Transactions and exceptions......Page 267
Retrying transactions......Page 272
Retrying with timeouts......Page 276
Transaction-local variables......Page 278
Transactional arrays......Page 279
Transactional maps......Page 281
Summary......Page 283
Exercises......Page 284
Chapter 8: Actors......Page 287
Working with actors......Page 288
Creating actor systems and actors......Page 291
Managing unhandled messages......Page 294
Actor behavior and state......Page 296
Akka actor hierarchy......Page 302
Identifying actors......Page 305
The actor lifecycle......Page 308
Communication between actors......Page 312
The ask pattern......Page 314
The forward pattern......Page 317
Stopping actors......Page 318
Actor supervision......Page 320
Remote actors......Page 326
Exercises......Page 330
Chapter 9: Concurrency in Practice......Page 333
Choosing the right tools for the job......Page 334
Putting it all together - a remote file browser......Page 339
Modeling the filesystem......Page 340
The server interface......Page 344
Client navigation API......Page 346
The client user interface......Page 350
Implementing the client logic......Page 354
Improving the remote file browser......Page 359
Debugging concurrent programs......Page 360
Deadlocks and lack of progress......Page 361
Debugging incorrect program outputs......Page 366
Performance debugging......Page 371
Summary......Page 378
Exercises......Page 379
Chapter 10: Reactors......Page 381
The need for reactors......Page 382
The Hello World program......Page 384
Event streams......Page 386
Lifecycle of an event stream......Page 387
Functional composition of event streams......Page 389
Reactors......Page 391
Defining and configuring reactors......Page 393
Using channels......Page 394
Schedulers......Page 397
Reactor lifecycle......Page 398
The logging service......Page 401
The clock service......Page 402
The channels service......Page 403
Custom services......Page 404
Custom server-client protocol......Page 407
Standard server-client protocol......Page 410
Creating a new connector......Page 411
Creating a protocol-specific reactor prototype......Page 412
Router protocol......Page 413
Two-way protocol......Page 415
Exercises......Page 419
Index......Page 422