Commit Graph

18 Commits (ec254d2555083ff258db9675fa43ad23888f0685)

Author SHA1 Message Date
Alex Trotsenko cdc30acbde Simplify QRingBuffer::peek()
Use a range-based for loop instead of index-based access.

Change-Id: Ie43aee540062eec4800f39915ebd42d5a3cae4b3
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
2018-02-22 18:34:30 +00:00
Alex Trotsenko 344acfb9fe QRingBuffer: replace some checks with asserts
To avoid the silent exits and potentially dangerous output values, the
caller must supply the correct parameters on input.

Change-Id: Ia9c56940adbf4ad34605a002dfc5c86b32c4658c
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
2018-01-10 20:21:31 +00:00
Alex Trotsenko 2d260eada8 Micro-optimize QRingBuffer::free()
Change the condition to strong equal, as 'bytes' was checked against
wrong value on the start of the function.

Change-Id: I4ec4768b9fff3292af233417c4a5862d72d4eeac
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
2018-01-09 15:52:18 +00:00
Alex Trotsenko 89b0364cde QRingBuffer: avoid reallocations of the data
Since its initial implementation, QRingBuffer had the following
fragilities in the architecture:

  - it does not guarantee validity of the pointers, if new data will
    be appended. As an example, passing an address of the QRingBuffer
    chunk as a parameter to the WriteFileEx() function on Windows
    requires the stability of the pointer. So, we can't add new data
    to the QRingBuffer until the overlapped operation completed
    (related issues were fixed for QWindowsPipeWriter and QSerialPort
    in 5.6 branch by introducing an intermediate byte array);
  - inefficient reallocations in reserve(), if a shared chunk was
    inserted in the queue (we can get a reallocation in the place
    where we don't expect it:

      char *writePtr = buffers.last().data() + tail;  <-  line #133

    ).

Proposed solution is to avoid reallocation by allocating a new
block instead. That was accomplished by introducing a QRingChunk
class which operates on a fixed byte array and implements head/tail
pointers strategy for each individual buffer in the queue. So,
QRingBuffer is no longer dependent on QByteArray's internal
shrink/growth algorithms.

Change-Id: I05abab0ad78e22e4815a196037dfc6eff85325d1
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
2017-12-30 10:15:10 +00:00
Alex Trotsenko 7dee74147e Micro-optimize QRingBuffer::chop()
Change the condition to strong equal, as 'bytes' was checked against
wrong value on the start of the function.

Change-Id: Iebd785665ac7bd0941ba4ffd3f315b12efc6ce0b
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
2017-12-19 18:07:59 +00:00
Alex Trotsenko 9cac65bc66 QRingBuffer::reserve(): remove superfluous assert
'bytes' is checked against MaxByteArraySize in the beginning and
remains unchanged in the function.

Change-Id: Ibd4091b95837db16cf45f845d485bfb189317125
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
2016-10-22 08:06:28 +00:00
Alex Trotsenko 3c6a7a96ef QRingBuffer: add packet mode
As a special case, setting the value of chunk size to zero forces
QRingBuffer to produce a separate QByteArray on each call which
appends the data. So, this enables a packet mode where portions of
data are stored independently from each other.

Change-Id: I2d0b331211901a289da7d4533e974f06830b5590
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
2016-07-23 09:05:13 +00:00
Anton Kudryavtsev f083830b8d CoreLib: use const (and const APIs) more
For CoW types const methods will be called.

Mark store_persistent_indexes() as const,
because this method does not modify the object.

Change-Id: Ic867913b4fb5aaebfbaaffe1d3be45cf7b646403
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
2016-04-18 04:49:19 +00:00
Alex Trotsenko ff76300a5c QRingBuffer::read(): remove unneeded byte array allocation
QRingBuffer already works fine with empty list of arrays.

Change-Id: I5cd388709686d2980efa3d5129c726e75c0b5c09
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
2016-02-24 11:42:55 +00:00
Alex Trotsenko 57ca755d2e QRingBuffer: add append(const char *, qint64) function
This allows to remove a code duplication in several places.

Change-Id: I49f56e951682dbd2968923654a12cba5199a2502
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
2016-02-01 20:45:21 +00:00
Jani Heikkinen 1a88b2f768 Updated license headers
From Qt 5.7 -> LGPL v2.1 isn't an option anymore, see
http://blog.qt.io/blog/2016/01/13/new-agreement-with-the-kde-free-qt-foundation/

Updated license headers to use new LGPL header instead of LGPL21 one
(in those files which will be under LGPL v3)

Change-Id: I046ec3e47b1876cd7b4b0353a576b352e3a946d9
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>
2016-01-15 12:25:24 +00:00
Alex Trotsenko 4116fe873e QRingBuffer: improve indexOf() performance
Use memchr() instead of scan cycle.

Change-Id: Ic77a3e5ad4c5f6c7d2a1df12d150eac45d620744
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
2015-09-03 18:31:49 +00:00
Alex Trotsenko c3d8ab78b8 QRingBuffer: avoid allocation in c'tor
Reduces creation time and memory consumption when the buffer is unused.
Robin's benchmark:

  QBENCHMARK {
      QFile file(filename);
  }

reports the following results (run with -median 10 -iterations 524288):

before: 0.00028 msecs per iteration (total: 149, iterations: 524288)
after:  0.00017 msecs per iteration (total: 93, iterations: 524288).

Change-Id: Ied4e7caeca794b94260b8fc59b3ba656f4719c30
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
2015-08-27 14:42:37 +00:00
Alex Trotsenko 526d9b52ce QRingBuffer: allow to search from any position
Change-Id: I348cd9da88fc81c3dd0789ce8cce9d80c4524e24
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@theqtcompany.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
2015-08-27 07:16:49 +00:00
Alex Trotsenko 964d767976 QRingBuffer::reserveFront(): do not leave empty array in buffer list
Fix the corner case when called on empty buffer.

Change-Id: I1316de7fbe69f3db40a7fdde06336e53d82675c9
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
2015-07-10 16:34:53 +00:00
Ulf Hermann ef0f7f4248 Unify QByteArray::MaxSize and MaxAllocSize
We have established the maximum size qAllocMore can deal with in
commit 880986be23 and we should use
it.

The maximum size for byte arrays is reduced by one byte as with
the previous code we could make qAllocMore produce ((1 << 31) - extra)
by passing (1 << 30). That is not a problem for qAllocMore itself
(as long as extra > 0) but it's hard to verify that no related
code casts the total sum back to signed int, which would overflow
to -1.

To make the compiler inline access to the maximum size, a private
enum MaxByteArraySize is provided, which can be used in internal
code.

This fixes the merge of commits
880986be23 and
c70658d301

Change-Id: Idb04856f7c2e53ef383063e7555d3083020ff2b7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
2015-06-16 14:30:45 +00:00
Alex Trotsenko ac4b28ce4d QRingBuffer: merge indexOf() overloads
Change-Id: Icfed4a29bc2ac95b3e0300eb4579751fe7e57e77
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
2015-05-28 13:45:47 +00:00
Alex Trotsenko e227b8ecf6 Deinline QRingBuffer class
Reduce the size of .text section in QtCore by 4.5KB and in QtNetwork
by 26.5KB.

Change-Id: If7998776166b9681c1e4b24c51d40444aa996d7a
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
2015-05-20 13:49:00 +00:00