1. 02 Apr, 2015 14 commits
    • Dave Watson's avatar
      stop in same thread · b2901a61
      Dave Watson authored
      Summary: In a couple places in ServerBootstrap there is code that needs to run in the EB, but if we are already in the EB, it's fine to run it inline.  Maybe this should be a method on EB directly?  There is runInEventBaseThreadAndWait(), but it explicitly disallows this usage.
      
      Test Plan: used in D1942242, deadlocks without this, since stop() was called in the same eb
      
      Reviewed By: yfeldblum@fb.com
      
      Subscribers: chalfant, doug, fugalh, folly-diffs@, jsedgwick, yfeldblum
      
      FB internal diff: D1947581
      
      Signature: t1:1947581:1427831021:d1d08ff9a4a00501d6be60670709fcb17af04134
      b2901a61
    • Joel Goguen's avatar
      Move OpenSSL uninitialization to a separate function · 3fc41801
      Joel Goguen authored
      Summary:
      The current behaviour of SSLContext is subject to a bug where an instance going
      out of scope at the wrong time can decrement the global refcount to 0, causing
      the destructor to destroy the SSL context. Instead, this requires callers to
      explicitly uninitialize the SSLContext instance and assume the risk of wrongly
      destroying the global SSL context.
      
      Test Plan:
      Tested with mcrouter
      
      Reviewed By: subodh@fb.com
      
      Subscribers: afrind, ssl-diffs@, folly-diffs@, yfeldblum, chalfant, dihde, melitam
      
      FB internal diff: D1949649
      
      Tasks: 6358211
      
      Signature: t1:1949649:1427854689:aea2dc801f63256ff64188b0f7a15121dcecee69
      3fc41801
    • Yuri Putivsky's avatar
      Get access to EventBaseManager object · 75ad72b0
      Yuri Putivsky authored
      Summary: as title
      
      Test Plan: run unit tests
      
      Reviewed By: yfeldblum@fb.com
      
      Subscribers: ming, fugalh, folly-diffs@, jsedgwick, yfeldblum, chalfant
      
      FB internal diff: D1955074
      75ad72b0
    • Daniel Pittman's avatar
      MPMCQueue - FPE to invalid_argument for 0 capacity · 13dda79b
      Daniel Pittman authored
      Summary:
      If an MPMCQueue was initialized with an explicit zero capacity, it would
      try to compute stride for zero and trigger SIGFPE which pretty fatally
      killed the process -- but in a way that required gdb to figure out the
      root cause.
      
      This replaces that with a std::invalid_argument exception, which
      includes a description of the problem and should make fixing this user
      error much faster.
      
      Test Plan:
      GTEST unit test added to verify behaviour; if this didn't work it would
      SIGFPE and abort the test script, which is probably a good indicator
      that something went wrong. :)
      
      fbconfig -r folly && fbmake runtests
      
      Reviewed By: ngbronson@fb.com
      
      Subscribers: chalfant, folly-diffs@, yfeldblum, rkomorn
      
      FB internal diff: D1930978
      
      Signature: t1:1930978:1427740315:cc06a8b9f3c314b956ae41f813b2f904d3e979c9
      13dda79b
    • Dave Watson's avatar
      Default accept function in Acceptor · 43989f9d
      Dave Watson authored
      Summary: Since Acceptor can be used for TCP or UDP, make an empty default TCP accept function so subclasses don't have to.
      
      Test Plan:
      built D1942242, no build errors
      
      contbuild
      
      Reviewed By: yfeldblum@fb.com
      
      Subscribers: doug, fugalh, folly-diffs@, jsedgwick, yfeldblum, chalfant
      
      FB internal diff: D1948940
      
      Signature: t1:1948940:1427498977:26b7bb23e3367ff6695dad86ebf0e60637815a7b
      43989f9d
    • Yedidya Feldblum's avatar
      EventBase::runImediatelyOrRunInEventBaseThreadAndWait. · cb2fe8d0
      Yedidya Feldblum authored
      Summary:
      [Folly] EventBase::runImediatelyOrRunInEventBaseThreadAndWait.
      
      When you have code that you need to run in the event loop and wait for it to finish, and you yourself might be in the event loop but might be in another thread instead.
      
      Test Plan:
      Unit tests:
      * `folly/io/async/test/EventBaseTest.cpp`.
      
      Reviewed By: davejwatson@fb.com
      
      Subscribers: folly-diffs@, yfeldblum, chalfant, agallagher, njormrod, ldbrandy, brettp, dougw
      
      FB internal diff: D1953110
      
      Signature: t1:1953110:1427751076:ad2c9f4d5b65ef952cba94b06be887672ee44583
      cb2fe8d0
    • Yuri Putivsky's avatar
      Fixing predicate inlining · 0ad80e7c
      Yuri Putivsky authored
      Summary:
      as title.
      
      Test Plan: run unit tests
      
      Reviewed By: yfeldblum@fb.com
      
      Subscribers: ming, fugalh, folly-diffs@, jsedgwick, yfeldblum, ridge@
      
      FB internal diff: D1946589
      0ad80e7c
    • Yuri Putivsky's avatar
      Extend IO pool with external optional event_base_manager · cecc9aaa
      Yuri Putivsky authored
      Summary: as title
      
      Test Plan: run unit tests
      
      Reviewed By: yfeldblum@fb.com
      
      Subscribers: ming, fugalh, folly-diffs@, jsedgwick, yfeldblum, chalfant
      
      FB internal diff: D1950610
      cecc9aaa
    • Dave Watson's avatar
      asyncudpserversocket reuse port · 3e3afca6
      Dave Watson authored
      Summary:
      AsyncUDPSocket supports reuse port, also make it available in AsyncUDPServerSocket.
      Has to happen before bind
      
      Test Plan:
      ?? it builds?
      
      Mutliple binds already work with reuseaddr, but load balancing doesn't work as well.  See http://lwn.net/Articles/542629/ for details
      
      Reviewed By: naizhi@fb.com
      
      Subscribers: doug, fugalh, folly-diffs@, jsedgwick, yfeldblum, chalfant
      
      FB internal diff: D1948932
      
      Signature: t1:1948932:1427473013:8c114458a0746bb2b6957db33c1834179d860c00
      3e3afca6
    • Hans Fugal's avatar
      Future::filter(A => bool) · 77c9cc67
      Hans Fugal authored
      Test Plan: new unit tests
      
      Reviewed By: davejwatson@fb.com
      
      Subscribers: chalfant, bmatheny, trunkagent, exa, folly-diffs@, yfeldblum, jsedgwick
      
      FB internal diff: D1828251
      
      Tasks: 6166893
      
      Signature: t1:1828251:1427475565:512463d5728482a40c1da2548a5bed91e7f92d60
      77c9cc67
    • Alexey Spiridonov's avatar
      Add CaptureFD for log testing (and some glog patterns) · 397a944b
      Alexey Spiridonov authored
      Summary:
      Without a gadget like this, it's really hard to test logging output. With it, it's really easy. I found about 50 callsites to the various functions across several projects, so folly seems appropriate.
      
      PS The patterns are functions for two reasons:
      - Static variables are a pain.
      - This leaves the option of adding an optional argument, so you can grep for a particular kind of error string.
      
      Test Plan: unit test
      
      Reviewed By: yfeldblum@fb.com
      
      Subscribers: folly-diffs@, yfeldblum
      
      FB internal diff: D1933439
      
      Signature: t1:1933439:1427345479:5b3d1c6566a026fdbccb16b382211688e327ea1a
      397a944b
    • Alexey Spiridonov's avatar
      Add EXPECT_{NO_,}_PCRE_MATCH macros · 133fc50c
      Alexey Spiridonov authored
      Summary: There are about 40 callsites to these across a couple of projects, and they seem generally useful.
      
      Test Plan: ```fbconfig folly/experimental/test && fbmake runtests```
      
      Reviewed By: yfeldblum@fb.com
      
      Subscribers: folly-diffs@, yfeldblum
      
      FB internal diff: D1933415
      
      Signature: t1:1933415:1427345307:6587eea3dac74c5d841950ace3c3501d6e3dbe4a
      133fc50c
    • Adam Simpkins's avatar
      TemporaryFile and TemporaryDirectory · bf0d2143
      Adam Simpkins authored
      Summary:
      TemporaryFile, TemporaryDirectory, and ChangeToTempDir should all be moveable
      objects, but not copiable.  Define default move constructors and move
      assignment operators for these classes.  This will prevent copy constructor and
      copy assignment operators from being implicitly defined.
      
      Test Plan:
      Used this in a new test to write a helper function which created and returned
      a new TemporaryFile object using the move constructor.
      
      Reviewed By: yfeldblum@fb.com
      
      Subscribers: doug, net-systems@, exa, folly-diffs@, yfeldblum
      
      FB internal diff: D1945134
      
      Signature: t1:1945134:1427342944:3428327e797ce4b3d362f9a2d2276de6d8b96137
      bf0d2143
    • Hannes Roth's avatar
      (Wangle) Reduce · 3e447ce4
      Hannes Roth authored
      Summary:
      1] The lambda should ble able to return a `Try<T>`. Maybe? Can a `then`
      return a `Try<T>` actually? Can fix this with `resultOf`. (Doubling the number of functions to 4.)
      
      2] `initial` and `func` have to be copyable.
      
      Test Plan: Added tests.
      
      Reviewed By: hans@fb.com
      
      Subscribers: trunkagent, folly-diffs@, jsedgwick, yfeldblum
      
      FB internal diff: D1870996
      
      Tasks: 6025252
      
      Signature: t1:1870996:1427318511:2ae5894b79022da88990835b26d35c4520fdbd29
      3e447ce4
  2. 25 Mar, 2015 13 commits
    • Noam Lerner's avatar
      Bump version to 32:0 · 2184167a
      Noam Lerner authored
      2184167a
    • Ben Maurer's avatar
      Add a pretty macro for deprecation · 014ffabd
      Ben Maurer authored
      Summary: Make it easy for people to mark code as deprecated
      
      Test Plan: Chose a random file and added the FOLLY_DEPRECATED macro to it
      
      Reviewed By: yfeldblum@fb.com
      
      Subscribers: ps, folly-diffs@, yfeldblum
      
      FB internal diff: D1943248
      
      Signature: t1:1943248:1427316689:b3305d134f374697e93d36bafbf0961eec1ef68a
      014ffabd
    • Sarang Masti's avatar
      Relax CHECK condition in stringAppendfImpl · 0dee3980
      Sarang Masti authored
      Summary:
      vsnprintf can return fewer bytes and bytes_used if
      we print a string containing '\0' using a width
      specifier.
      
      Test Plan: -- ran all tests
      
      Reviewed By: andrei.alexandrescu@fb.com
      
      Subscribers: folly-diffs@, yfeldblum
      
      FB internal diff: D1915035
      
      Signature: t1:1915035:1426799341:4aaea928c4bdde1998bf66cf9e2732a53572c6e3
      0dee3980
    • Dave Watson's avatar
      httpserver on serverbootstrap (2) · 71b91824
      Dave Watson authored
      Summary:
      Original diff D1800100, reverted in D1895181.  Issue seems to have been caused by a copy constructor issue.
      
      Fixes: Remove copy constructor, move contructor only.  Separate stop() and join(), since join() can happen only after all stop()s have completed when reusing the same IOThreadPoolExecutors.
      
      Test Plan: build and unit tests of relevant product
      
      Reviewed By: praveenr@fb.com
      
      Subscribers: trunkagent, doug, fugalh, alandau, bmatheny, mshneer, folly-diffs@, jsedgwick, yfeldblum
      
      FB internal diff: D1901718
      
      Tasks: 6431975
      
      Signature: t1:1901718:1426885577:46b63bfe117df207be3d273b953c100249c1a7da
      
      Blame Revision: D1895181
      71b91824
    • Alexey Spiridonov's avatar
      Add ChangeToTempDir to TestUtil · 87a4b661
      Alexey Spiridonov authored
      Summary: It's convenient to be able to write tempfiles in the current directory. This provides a one-liner way of doing that in tests.
      
      Test Plan: unit test
      
      Reviewed By: yfeldblum@fb.com
      
      Subscribers: simpkins, folly-diffs@, yfeldblum
      
      FB internal diff: D1931918
      
      Signature: t1:1931918:1426913634:f988fb3c5061f5909e309dcaf42742d9b2ed18c6
      87a4b661
    • Andrii Grynenko's avatar
      Make folly::Singleton DFATAL as late as possible · 278d263c
      Andrii Grynenko authored
      Summary: We want to print all destructor stack-traces if Singleton destruction happens eventually (even after destroyInstances() was done).
      
      Test Plan:
      unit test
      
      Reviewed By: chip@fb.com
      
      Subscribers: folly-diffs@, yfeldblum
      
      FB internal diff: D1929881
      
      Signature: t1:1929881:1426878091:5993d544c0f84bdbf8bcdd420ef01fb7bf88ac3f
      278d263c
    • Dave Watson's avatar
      Udp Acceptor · 4abb4669
      Dave Watson authored
      Summary:
      major changes:
      
      1) ServerSocketFactory and AsyncSocketBase to abstract the differences between UDP and TCP async socket.  Could possibly push some of this to the sockets themselves eventually
      2) pipeline() is a pipeline between accept/receive of a UDP message, and before sending it to workers.  Default impl for TCP is to fan out to worker threads.  This is the same as Netty.  Since we don't know if the data is a TCP socket or a UDP message, it's a void*, which sucks (netty uses Object msg, so it isn't any different).
      
      Test Plan: Added lots of new tests.  Doesn't test any data passing yet though, just connects/simple receipt of UDP message.
      
      Reviewed By: hans@fb.com
      
      Subscribers: alandau, bmatheny, mshneer, jsedgwick, yfeldblum, trunkagent, doug, fugalh, folly-diffs@
      
      FB internal diff: D1736670
      
      Tasks: 5788116
      
      Signature: t1:1736670:1424372992:e109450604ed905004bd40dfbb508b5808332c15
      4abb4669
    • Dave Watson's avatar
      fix service memory leak · 3e3b5e35
      Dave Watson authored
      Summary:
      This code is only used in a test so far.
      
      Basically it looks like Pipeline has some dependency issues - any addBack() pipelines have to be deleted *after* the main pipeline is destroyed.  Ideally if the pipeline is already closed, the destruction order wouldn't matter.  There is currently no removeBack() call either.   This is a quick fix for the test to just delete stuff in the right order, we can discuss a better solution when @jsedgwick returns
      
      Test Plan: fbconfig --sanitize=address --with-project-version=clang:3.5 --clang folly/wangle/service && fbmake runtests
      
      Reviewed By: hans@fb.com
      
      Subscribers: trunkagent, doug, fugalh, folly-diffs@, yfeldblum, jsedgwick
      
      FB internal diff: D1903200
      
      Tasks: 6415578
      
      Signature: t1:1903200:1426528298:e109dcc0ec586a505a26cd95a6f20434d22cbd37
      3e3b5e35
    • Alexey Spiridonov's avatar
      Add comment about djb2 hash · db66df3b
      Alexey Spiridonov authored
      Summary:
      In my tests, using djb2 was much worse for any sizable workload. Just use SpookyHashV2.
      
      Test Plan: comment only
      
      Reviewed By: tudorb@fb.com
      
      Subscribers: trunkagent, folly-diffs@, yfeldblum
      
      FB internal diff: D1906439
      
      Signature: t1:1906439:1426117575:f88b7b28b578092c1716433e21150d423d4e94a7
      db66df3b
    • Sean Cannella's avatar
      SocketAddress::anyAddress should be a method · 5333a914
      Sean Cannella authored
      Summary:
      Calling getaddrinfo from a static constructor is not the most
      reliable thing to do. Stop doing it.
      
      Test Plan: existing tests
      
      Reviewed By: davejwatson@fb.com
      
      Subscribers: dancol, mzlee, shikong, kmdent, fma, bmatheny, benyluo, ranjeeth, folly-diffs@, jsedgwick, yfeldblum
      
      FB internal diff: D1924578
      
      Tasks: 6534662
      
      Signature: t1:1924578:1426718586:d73bc2f001095e66fa77fde9c027af050cc26d2a
      5333a914
    • Hannes Roth's avatar
      (Wangle) Clean up move constructors · efecbe5f
      Hannes Roth authored
      Summary: I thought this might fix #6120972. But it doesn't. Still a bit of a cleanup in my opinion.
      
      Test Plan: Run all the tests?
      
      Reviewed By: hans@fb.com
      
      Subscribers: trunkagent, folly-diffs@, jsedgwick, yfeldblum
      
      FB internal diff: D1907259
      
      Signature: t1:1907259:1426613567:9e33fe7e9e8a36ba006d4aee604086a56f128893
      efecbe5f
    • Andrey Goder's avatar
      Support 'min ms to log' · f6da18f2
      Andrey Goder authored
      Summary:
      Sometimes we only want to log if enough time has passed, e.g. when logging
      inside of a loop doing work to detect if things are slow. Add an option for
      that.
      
      Test Plan:
      build and unit tests of folly/experimental
      
      Reviewed By: lesha@fb.com
      
      Subscribers: trunkagent, folly-diffs@, yfeldblum
      
      FB internal diff: D1909055
      
      Signature: t1:1909055:1426627731:6d3ad94fd71967ec89ffebc90cd2907dd1631d36
      f6da18f2
    • Alexey Spiridonov's avatar
      Fix logFormat · 816b97a7
      Alexey Spiridonov authored
      Summary: Ooops during port ;)
      
      Test Plan: unit test
      
      Reviewed By: agoder@fb.com
      
      Subscribers: trunkagent, folly-diffs@, yfeldblum
      
      FB internal diff: D1905639
      
      Signature: t1:1905639:1426171227:a6e415046a85f098ac090f069476204fb0367c42
      816b97a7
  3. 18 Mar, 2015 13 commits
    • Andre Azevedo's avatar
      Bump version to 31:0 · 6001c511
      Andre Azevedo authored
      6001c511
    • Nicholas Ormrod's avatar
      Fixed README download link to get the correct GTest version · ad384398
      Nicholas Ormrod authored
      Summary: Signed-off-by: Nicholas Ormrod <njormrod@fb.com>
      
      Test Plan: Clicked link, gtest started downloading
      
      Reviewed By: markisaa@fb.com
      
      Subscribers: sdwilsh, folly-diffs@, yfeldblum
      
      FB internal diff: D1901849
      
      Tasks: 6255850
      
      Signature: t1:1901849:1426097071:e887ed8749c70d5e15877082ac0175ce3b56647e
      ad384398
    • Praveen Kumar's avatar
      BackoffTimeout disallow copy, move, default ctor · e3d118ed
      Praveen Kumar authored
      Summary:
      BackoffTimeout disallow copy construction, copy assignment, move
      construction, move assignment, and default construction.
      
      Closes https://github.com/facebook/folly/pull/146
      
      Test Plan: runtests
      
      Reviewed By: ldbrandy@fb.com
      
      Subscribers: lins, anca, folly-diffs@, yfeldblum
      
      FB internal diff: D1912521
      
      Signature: t1:1912521:1426268413:6edb2d8203d1efd1e825816f03be115ac46e55ca
      e3d118ed
    • Praveen Kumar's avatar
      We might avoid some temporaries · 4cc84128
      Praveen Kumar authored
      Summary:
      It seems we might avoid temporaries.  To do so we pass arguments
      directly to constructors with the help of emplace_back member.
      
      Test Plan:
      all folly/tests, make check for 37 tests, passed.
      
      Closes https://github.com/facebook/folly/pull/150
      
      Reviewed By: ldbrandy@fb.com
      
      Subscribers: lins, anca, folly-diffs@, yfeldblum
      
      FB internal diff: D1912505
      
      Signature: t1:1912505:1426268158:086882bb53f3d79c3f3b7b2c362318f09b5ee3be
      4cc84128
    • Praveen Kumar's avatar
      AsyncServerSocket disallow copy, move, and default ctor · c2a60049
      Praveen Kumar authored
      Summary:
      AsyncServerSocket disallow copy construction, copy assignment,
      move construction, move assignment, and default
      construction.
      
      Closes https://github.com/facebook/folly/pull/148
      
      Test Plan: all folly/tests, make check for 37 tests, passed.
      
      Reviewed By: ldbrandy@fb.com
      
      Subscribers: lins, anca, folly-diffs@, yfeldblum
      
      FB internal diff: D1912488
      
      Signature: t1:1912488:1426267982:a9690ce9429016f89630f0ded64b7be9ff80c39d
      c2a60049
    • Alecs King's avatar
      fix typo: add backslash to Makefile.am · 72683c85
      Alecs King authored
      Summary: backslash
      
      Test Plan: tests
      
      Reviewed By: aap@fb.com
      
      Subscribers: folly-diffs@, yfeldblum
      
      FB internal diff: D1920872
      
      Signature: t1:1920872:1426624366:c984fecb5bd0c292d5a8309fb320a48872fff6db
      
      Blame Revision: D1890511
      72683c85
    • Alecs King's avatar
      Add StringKeyedUnorderedMap to Makefile · cf6ee69e
      Alecs King authored
      Test Plan:
      unit tests
      
      Reviewed By: bwatling@fb.com
      
      Subscribers: stepan, folly-diffs@, yfeldblum, trunkagent, vikas, alikhtarov
      
      FB internal diff: D1890511
      
      Tasks: 6311387
      
      Signature: t1:1890511:1425924980:71af7c12a09a86b280dc3c9a9ef0756bf56bf639
      cf6ee69e
    • Hans Fugal's avatar
      (folly osx) test for the zip, not the dir · a1119563
      Hans Fugal authored
      Summary: Apparently `configure` creates this subdirectory and then the curl and unzip commands don't run, and then `make check` fails. Instead, do it if the zip file doesn't exist.
      
      Test Plan:
      git clone https://github.com/facebook/folly.git
      cd folly/folly
      /path/to/this/bootstrap-osx-homebrew.sh
      make
      make check
      
      Reviewed By: andrei.alexandrescu@fb.com
      
      Subscribers: exa, folly-diffs@, yfeldblum, davejwatson
      
      FB internal diff: D1882472
      
      Signature: t1:1882472:1425920470:bdab25967d3b8e52c690d5627168077c65829b92
      a1119563
    • James Sedgwick's avatar
      exceptionStr(exception_wrapper) · ae823da9
      James Sedgwick authored
      Summary: for consistency with exception and exception_ptr functions provided in String.h
      
      Test Plan: unit
      
      Reviewed By: vloh@fb.com
      
      Subscribers: trunkagent, folly-diffs@, yfeldblum
      
      FB internal diff: D1905087
      
      Tasks: 5961362
      
      Signature: t1:1905087:1426101740:670ceab5140250bbecdd1247025d3d70b7774690
      ae823da9
    • Jeroen Vaelen's avatar
      extend future api with Future<T>::poll · 66047c6a
      Jeroen Vaelen authored
      Summary:
      Added folly::Future<T>::poll() function with the following semantics:
      poll() checks if the promise has been fulfilled, if so it will extract the value of the resulting Try<T> to construct a new Try<T> that is wrapped in an Optional<Try<T>>. If the promise has not been fulfilled an empty Optional is returned.
      
      Test Plan: Added two tests to SugarTest.cpp: one where the promise has been fulfilled and one where it hasn't.
      
      Reviewed By: hannesr@fb.com
      
      Subscribers: trunkagent, folly-diffs@, jsedgwick, arturg, yfeldblum
      
      FB internal diff: D1909480
      
      Tasks: 6166875
      
      Signature: t1:1909480:1426280247:6b239c0f1a15c25ce7664afb4bfb3899993c5775
      66047c6a
    • Matt Dordal's avatar
      Add ctor to CPUThreadPoolExecutor to enable custom queue sizes · aae7c5b3
      Matt Dordal authored
      Summary:
      Seems useful to do without passing in a totally custom queue. Makes
      the client code a bit simpler.
      
      Test Plan: used it, saw low memory usage and no crash
      
      Reviewed By: davejwatson@fb.com
      
      Subscribers: trunkagent, iaroslav, fugalh, folly-diffs@, jsedgwick, yfeldblum, slarsen
      
      FB internal diff: D1907874
      
      Signature: t1:1907874:1426268010:3159ae339b51f5dbc7fe034644bbc968b92b072c
      aae7c5b3
    • Naizhi Li's avatar
      Add support for iovec for UDP send in folly::AsyncUDPSocket · 383ffb34
      Naizhi Li authored
      Summary:
      I will be using multi-buf UDP send soon, so adding the
      support in folly::AsyncUDPSocket
      
      Test Plan: Unit tests and turn server
      
      Reviewed By: davejwatson@fb.com
      
      Subscribers: trunkagent, folly-diffs@, yfeldblum
      
      FB internal diff: D1907189
      
      Signature: t1:1907189:1426266951:046198e0a009fef085ac7eb44f054c67dfb16ba3
      383ffb34
    • Adam Simpkins's avatar
      add Cursor::isAtEnd() · efca08ae
      Adam Simpkins authored
      Summary:
      Add a helper method to efficiently check if the cursor is at the end of the
      IOBuf chain.  This is equivalent to (cursor.totalLength() > 0), but it doesn't
      need to walk the entire chain just to tell if it is at the end or not.
      
      Test Plan: Updated the unit tests to contain some checks for isAtEnd().
      
      Reviewed By: jasmeetbagga@fb.com
      
      Subscribers: trunkagent, doug, net-systems@, exa, folly-diffs@, yfeldblum
      
      FB internal diff: D1875345
      
      Signature: t1:1875345:1425006512:49ac246fd0ac7937fdcd6cf1359a841f048c444e
      efca08ae