Summary:
Each sequence of tuples within an entires set is terminated with (0,
0) according to the DWARF standard (see 7.20 in
http://www.dwarfstd.org/doc/DWARF4.pdf).

Reviewed By: ot, luciang

Differential Revision: D4014952

fbshipit-source-id: c4b034c94adc4a0d9b052456c02919a54a79eaf1

Summary: This feature already exists in detail, move it to public instead.

Reviewed By: andriigrynenko

Differential Revision: D4013691

fbshipit-source-id: 1779cc53d114ddc97993b41e0ad63c104008f6b0

Reviewed By: yfeldblum

Differential Revision: D4013256

fbshipit-source-id: 771f9becfa9e7676439209dfbf4a746c110d629d

Summary:
BoringSSL returns `const SSL_CIPHER*` from sk_SSL_CIPHER_value().
Closes https://github.com/facebook/folly/pull/492

Reviewed By: yfeldblum

Differential Revision: D4009712

Pulled By: Orvid

fbshipit-source-id: cca2e8cb6aab0a459dca55b8f23ef57fa5c8251f

Summary:
`SSL_SESSION_up_ref()` in both BoringSSL and OpenSSL 1.1.0 takes a
`SSL_SESSION*`.
Closes https://github.com/facebook/folly/pull/493

Reviewed By: yfeldblum

Differential Revision: D4009706

Pulled By: Orvid

fbshipit-source-id: 68ea201821e7a6d5835a79b34187344ba251e239

Summary:
Currently only shortcut levels are properly handled, others result in
using level 1.

Reviewed By: yfeldblum

Differential Revision: D4008123

fbshipit-source-id: 37845eeec139007738f99e72ecfb969c6a2e5652

Summary:
When terminating because we were told to rethrow a nonexistent exception, we
now print that to `std::cerr` for the benefit of users on platforms which do not dump a stack trace on
`std::terminate`

Reviewed By: yfeldblum

Differential Revision: D4001087

fbshipit-source-id: 5b834cfc75bf42bec06a49ac9db55789a83df180

Summary: I thought we wouldn't need this but it turns out Thrift Frozen2 iterators return proxies (it's proxies all the way down). Thanks to ericniebler for trick.

Reviewed By: yfeldblum

Differential Revision: D4005700

fbshipit-source-id: 1911996afa075c1d819a3aaea2ee924bc2ae2f20

Summary:
There are two changes here.
The first is to eliminate `detail::DEFAULT_CLOCK_ID` from `Benchmark.[cpp|h]` as Sierra defines `clockid_t` as an enum type, which means that calling `clock_gettime(detail::DEFAULT_CLOCK_ID` would fail, because the enums are incompatible. As this was being used as a default, but is not actually changable anywhere, I just got rid of `detail::DEFAULT_CLOCK_ID` entirely.
The second is to move `portability/BitsFunctexcept.cpp` into `libfollybase_la_SOURCES`, because it's needed for generating the fingerprint tables.

Reviewed By: yfeldblum

Differential Revision: D4004843

fbshipit-source-id: b2a9c33f8e516d8eb3cdc5ab093f4946ac9ed37e

Summary:
I added kFatalSignalHandlerCacheSize in {D3984649}, and chose a big
number to satisfy most use-cases. But the size increase is non-trivial.

Memory usage:

- before: 5.1 MB in folly::symbolizer::SignalSafeElfCache::SignalSafeElfCache
- after: 80.0 MB in folly::symbolizer::SignalSafeElfCache::SignalSafeElfCache

Switch to a dynamic approach and everyone pays for what they use.

https://github.com/bminor/glibc/blob/ee19f1de0d0da24114be554fdf94243c0ec6b86c/elf/rtld-debugger-interface.txt#L10-L20
```
The r_debug structure contains (amongst others) the following fields:

  struct link_map *r_map:
    A linked list of loaded objects.

  enum { RT_CONSISTENT, RT_ADD, RT_DELETE } r_state:
    The current state of the r_map list.  RT_CONSISTENT means that r_map
    is not currently being modified and may safely be inspected.  RT_ADD
    means that an object is being added to r_map, and that the list is
    not guaranteed to be consistent.  Likewise RT_DELETE means that an
    object is being removed from the list.
```

https://github.com/bminor/glibc/blob/ee19f1de0d0da24114be554fdf94243c0ec6b86c/elf/rtld.c#L303-L307
```
  /* Call the OS-dependent function to set up life so we can do things like
     file access.  It will call `dl_main' (below) to do all the real work
     of the dynamic linker, and then unwind our frame and run the user
     entry point on the same stack we entered on.  */
  start_addr = _dl_sysdep_start (arg, &dl_main);
```

dl_main: https://github.com/bminor/glibc/blob/ee19f1de0d0da24114be554fdf94243c0ec6b86c/elf/rtld.c#L1192-L1199
```
  /* Initialize the data structures for the search paths for shared
     objects.  */
  _dl_init_paths (library_path);

  /* Initialize _r_debug.  */
  struct r_debug *r = _dl_debug_initialize (GL(dl_rtld_map).l_addr,
					    LM_ID_BASE);
  r->r_state = RT_CONSISTENT;
...

  /* We start adding objects.  */
  r->r_state = RT_ADD;
  _dl_debug_state ();
  LIBC_PROBE (init_start, 2, LM_ID_BASE, r);

...

  /* Notify the debugger all new objects are now ready to go.  We must re-get
     the address since by now the variable might be in another object.  */
  r = _dl_debug_initialize (0, LM_ID_BASE);
  r->r_state = RT_CONSISTENT;
  _dl_debug_state ();
  LIBC_PROBE (init_complete, 2, LM_ID_BASE, r);

```

Reviewed By: bixue2010

Differential Revision: D3996974

fbshipit-source-id: e24d72e3cc0339e4cf1acdd2f4c9a7ebfcfdf739

Summary:
Compiling with gcc's proposed -Wshadow-compatible-local option
exposed some fix-worthy warnings. Rename to avoid the shadowing.

Reviewed By: evilmucedin

Differential Revision: D3999026

fbshipit-source-id: 26cb3033ba8c5538cc9217993f2fda6aef954a8f

Summary: converting add(value&&) to add(value) to make it easier for callsites to use.

Reviewed By: A5he

Differential Revision: D4000416

fbshipit-source-id: c66f4d93d1223286bbc786d17f65ed02a63cc794

Summary: this particular test fails reliably for fbandroid. Modifying the code in fbcode, assuming it will be synced promptly.

Reviewed By: edelron

Differential Revision: D4000722

fbshipit-source-id: fca5e691ea5c972ddd245acee1c17720730539d4

Summary:
The bug report in t13764686 shows that `folly::StringPiece().str()` causes undefined behavior by passing nullptr into memcpy: the default-initialized StringPiece has two null pointers, which will call `string(char*, size)` with nullptr and 0. This gets forwarded to `podCopy` in fbstring, which calls memcpy and has undefined behavior.

The call pattern `string(nullptr, 0)` is not illegal (note: that syntax is ambiguous, as the literal `0` can be converted to a pointer). Prevent this legal call pattern from causing undefined behavior in fbstring.

This diff puts asserts in podCopy to catch errors, and ensures that current podCopy callsites ensure that the pointer is non-null.

Most podCopy callsites do not need to guarded, since the size is guaranteed to be greater than 0 (which will hard crash instead). The interesting callsite is in `initMedium`, because there is a mode (disableSSO) which will allocate empty strings on the heap, so we need to add a guard there.

Reviewed By: luciang

Differential Revision: D3996440

fbshipit-source-id: b311a311973d1d969542245c72035c5b38da58e3

Summary:
Interface:
- Got rid of std::function reclamation functions and added a Deleter template parameter.
- Got rid of the flush() member functions of hazptr_domain
- Added a lock-free non-bool member function to get a protected pointer.
Implementation:
- Implemented the interface changes.
- Changed the order of accesses in reading the shared list of objects vs reading the hazard pointers. I think the previous order would have allowed recently protected objects to be reclaimed incorrectly.
Updated the examples and tests accordingly.

Reviewed By: davidtgoldblatt

Differential Revision: D3981284

fbshipit-source-id: 35ff60da3aea1f67c58d82437dda58f6d8b07bf5

Summary:
The definition of `throwException()` is changed to add the `[[noreturn]]`
attribute for consistency with `std::rethrow_exception`. If the
`exception_wrapper` contains an exception, that is rethrown; if not, then
`std::terminate` is called.

An alternative design which threw an exception if the `exception_wrapper` did not contain an exception was rejected because of the ambiguity it introduced as to whether the exception thrown was wrapped or not.

Benchmarks before:

```

============================================================================
folly/test/ExceptionWrapperBenchmark.cpp        relative  time/iter  iters/s
============================================================================
exception_ptr_create_and_test                                1.45us  689.01K
exception_wrapper_create_and_test               4337.80%    33.46ns   29.89M
----------------------------------------------------------------------------
exception_ptr_create_and_test_concurrent                   342.99us    2.92K
exception_wrapper_create_and_test_concurrent     101.41%   338.21us    2.96K
----------------------------------------------------------------------------
exception_ptr_create_and_throw                               3.05us  327.89K
exception_wrapper_create_and_throw               140.22%     2.17us  459.77K
exception_wrapper_create_and_cast               8956.80%    34.05ns   29.37M
----------------------------------------------------------------------------
exception_ptr_create_and_throw_concurrent                  372.68us    2.68K
exception_wrapper_create_and_throw_concurrent    102.54%   363.44us    2.75K
exception_wrapper_create_and_cast_concurrent     110.93%   335.97us    2.98K
============================================================================
```

and after:

```

============================================================================
folly/test/ExceptionWrapperBenchmark.cpp        relative  time/iter  iters/s
============================================================================
exception_ptr_create_and_test                                1.46us  684.09K
exception_wrapper_create_and_test               4368.84%    33.46ns   29.89M
----------------------------------------------------------------------------
exception_ptr_create_and_test_concurrent                   341.20us    2.93K
exception_wrapper_create_and_test_concurrent      99.88%   341.60us    2.93K
----------------------------------------------------------------------------
exception_ptr_create_and_throw                               3.08us  324.93K
exception_wrapper_create_and_throw               106.93%     2.88us  347.46K
exception_wrapper_create_and_cast               9532.05%    32.29ns   30.97M
----------------------------------------------------------------------------
exception_ptr_create_and_throw_concurrent                  363.73us    2.75K
exception_wrapper_create_and_throw_concurrent    101.04%   360.00us    2.78K
exception_wrapper_create_and_cast_concurrent     104.50%   348.07us    2.87K
============================================================================
```

Reviewed By: yfeldblum

Differential Revision: D3923939

fbshipit-source-id: 6fc58ac571e59e4122f1fbd194c678e3a3841057

Summary:
Prior to this change, any nested use of FOR_EACH would
induce a shadowed declaration for each of the two local
state variables it declares.

This makes the names of those variables __LINE__-dependent,
so that there is no shadowing, as long as each nested use
is on a different line.

This also adds a new test that (prior to this change) would fail to
compile with an option like -Werror=shadow-compatible-local.

Since this change relies on cpp token concatenation, I have included
The fix defines a new helper macro, _FE_ANON, to derive each new variable
name. I wondered whether to do this for every other FOR_* macro here, but
since so far, I have encountered more than 10 cases of nested FOR_EACH
uses in a large corpus, but no nesting of any other FOR_* macro, I am
content to do it only for this one.

Reviewed By: yfeldblum

Differential Revision: D3992956

fbshipit-source-id: f26fba89bc661bb9d22747dec0acdcf8c648fb83

Summary:
In HHWheelTimer::scheduleTimeout, remove the declaration of the
unused variable, "prev".

Reviewed By: yfeldblum

Differential Revision: D3987409

fbshipit-source-id: 3a9291bf104e6865d608adfb6118609faa0aea96

Summary:
We are using `bm_max_iters` in folly and other part of the code in fbcode but it didn't really exist in Benchmark.cpp. For example: https://github.com/facebook/folly/blob/master/folly/test/function_benchmark/main.cpp#L29

This patch adds back this functionality.

This diff depends on D3990600.

Reviewed By: yfeldblum

Differential Revision: D3989499

fbshipit-source-id: d2303b2bebb196e84a592d54a72af68171971491

Summary: This patch prepares the later diff which will add a new flag. Just make things nice.

Reviewed By: igorsugak

Differential Revision: D3990600

fbshipit-source-id: d4f53a5b44708ca025e4f6615d161b24de685931

Summary:
Remove all code that create large strings.

This diff does not remove code that deals with large strings, so that the transition to libgcc will be smoother. Note that the FBSTRING_ASSERT inside of setCapacity will be disabled in the libgcc build.

Reviewed By: luciang, ot

Differential Revision: D3977459

fbshipit-source-id: 09c1712854b31509138c5cc8baf19caf3c715bb6

folly: symbolizer: increase default signal-handler symbolizer elf file cache size (make it work with large number of .so)

Summary:
Bump the default size so we can symbolize symbols in dynamically linked
binaries with lots and lots of shared libraries :)

folly/experimental/symbolizer/ElfCache.h
```
  * Will not grow; once the capacity is reached, lookups for files that
  * aren't already in the cache will fail (return nullptr).
  class SignalSafeElfCache
```

Reviewed By: ot, philippv

Differential Revision: D3984649

fbshipit-source-id: acdca9b9adf6c16f3a1556bc3f57b28844cdd9cc

Summary: We want to fail fast if we attempt to stop a scheduler that was not running

Reviewed By: yfeldblum

Differential Revision: D3976919

fbshipit-source-id: d8aa8b35aa9e22758e6a7ef64f48a7dd6d990b1c

Summary:
When `delayed` is called on the Future, the underlying `futures::sleep` call runs on a timer thread, and the resulting callback is called on the same thread. Therefore, in the following sequence:

  f.via(&someExecutor).within(one_ms).then([&]() { /* [1] */ })

The code in [1] is not running in someExecutor. This can cause confusion by users of the library who expect the initial `via` to be sticky.

This change returns to the prior `Executor` after `delayed` is finished.

Reviewed By: yfeldblum

Differential Revision: D3979179

fbshipit-source-id: e1448f5603f0c9440490ae3bf0e670687f4179f3

Summary: Fix shadowing warnings.

Reviewed By: russoue

Differential Revision: D3979165

fbshipit-source-id: 19a3940e210e4d5a698dbc0e6d74b317a74a94fa

Summary:
When `delayed` is called on the Future, the underlying `futures::sleep` call runs on a timer thread, and the resulting callback is called on the same thread. Therefore, in the following sequence:

  f.via(&someExecutor).within(one_ms).then([&]() { /* [1] */ })

The code in [1] is not running in someExecutor. This can cause confusion by users of the library who expect the initial `via` to be sticky.

This change returns to the prior `Executor` after `delayed` is finished.

Reviewed By: yfeldblum

Differential Revision: D3979179

fbshipit-source-id: 936ff5626e8ac377ffb15babf573349466984e3a

Summary: The attribute `__returns_nonnull__` is only applicable for gcc 4.9 or later (https://gcc.gnu.org/onlinedocs/gcc-4.8.5/gcc/Function-Attributes.html#Function-Attributes)

Reviewed By: ot

Differential Revision: D3976598

fbshipit-source-id: 3c678a11c5046e5a8b7686327dbb3ebc9b598616

Summary: It's bad mkey. Says so on the tin can. Alert/annoy its users.

Reviewed By: yfeldblum, ot

Differential Revision: D3973625

fbshipit-source-id: 23f4e16182749d016084fcb378a1170ff402c259

Summary: no uses remain in folly

Reviewed By: yfeldblum

Differential Revision: D3972507

fbshipit-source-id: 356ddbcf24c217b0f589989ab6cc3910d0f7baf3

Updated example and methodology for using DeterministicSchedule support for auxiliary data and global invariants

Summary:
Depends on D3792669

Updating the test and methodology based on the experience with fine-grained testing dynamic MPMCQueue using DeterministicSchedule's support for auxiliary data and global invariants.

Updates D3675447

Reviewed By: djwatson

Differential Revision: D3794217

fbshipit-source-id: d2862895cb8dea120e758beeb24d6ae15191b013

Summary: Initialize Optional internal memory, so that "un-initialized memory" tools don't flag its callsites.

Reviewed By: yfeldblum

Differential Revision: D3960462

fbshipit-source-id: 3bd0109959fb93e040fa2e874f586b3508e46dd2

Summary:
folly::StringPieceHash has a large comment explaining why not to use it, but it's not marked as deprecated.

It's also conveniently named StringPieceHash and not StringPieceHashDEPRECATED so new uses appear from time to time.

Let's nuke the default before it does more damage.

Reviewed By: yfeldblum

Differential Revision: D3967239

fbshipit-source-id: 04b0564fdf2a70f1195ef2afdff092bc63cde975

Summary: #accept2ship

Reviewed By: bixue2010

Differential Revision: D3971138

fbshipit-source-id: 25e0aeddebf001dd8e27a4939842915ccf1000ad

Summary:
The following thrift file doesn't work:
  typedef set<i32> (cpp.template = "folly::sorted_vector_set") IntSet
  struct Test {
    1: map<i32, IntSet> m = {7: [1, 2]},
  }

The generated file looks like this:
  Test()
      : m(std::initializer_list<
          std::pair<const int32_t, folly::sorted_vector_set<int32_t>>>{
          {7, std::initializer_list<int32_t>{1, 2}}}) {}

Given that `std::set` allows implicit construction from `std::initializer_list`, it's probably okay to make `folly::sorted_vector_set` the same.

Reviewed By: ot

Differential Revision: D3968054

fbshipit-source-id: 978d59a7e545e44d603eeb9671815ac7f2c57342

Summary:
Enabling the proposed-for-upstream gcc -Wshadow-local option exposes this shadowing:
```
folly/io/async/AsyncSocket.cpp: In member function 'virtual void folly::AsyncSocket::connect(folly::AsyncSocket::ConnectCallback*, const folly::SocketAddress&, int, const OptionMap&, const folly::SocketAddress&)':
folly/io/async/AsyncSocket.cpp:421:11: error: declaration of 'rv' shadows a previous local [-Werror=shadow-compatible-local]
folly/io/async/AsyncSocket.cpp:364:9: error: shadowed declaration is here [-Werror=shadow-compatible-local]
```

Reviewed By: ngoyal, knekritz

Differential Revision: D3963873

fbshipit-source-id: 85b3ab1fc3b200b81615a00d66a183cc9c792a90

Summary:
This matches what the STL does with e.g. std::vector::swap() and std::shared_ptr::swap().

http://en.cppreference.com/w/cpp/container/vector/swap
http://en.cppreference.com/w/cpp/memory/shared_ptr/swap

Should be relatively uncontroversial, I would think.
Closes https://github.com/facebook/folly/pull/489

Reviewed By: magedm

Differential Revision: D3963285

Pulled By: yfeldblum

fbshipit-source-id: 3fa6bf77e66fa9a673cb648b0bf87b1db3caa6c8

Summary:
gcc's -Wshadow (and the under-review -Wshadow-local) would evoke this:
```
folly/io/Compression.cpp:650:9: error: declaration of 'rc' shadows a previous local [-Werror=shadow-compatible-local]
folly/io/Compression.cpp:637:7: error: shadowed declaration is here [-Werror=shadow-compatible-local]
folly/io/Compression.cpp:566:9: error: declaration of 'rc' shadows a previous local [-Werror=shadow-compatible-local]
folly/io/Compression.cpp:548:7: error: shadowed declaration is here [-Werror=shadow-compatible-local]
```
In each case, I removed the "int" from the latter declaration.

Reviewed By: philippv

Differential Revision: D3966308

fbshipit-source-id: 584cb9ffe8ba0e56914223c440efabe9e0de6b17

Summary: Outline all the non-trivial constructor and the destructor, `assign()`, and `append()` to reduce code size. The fast path of copy, and moves, are instead still inlined.

Reviewed By: philippv

Differential Revision: D3896612

fbshipit-source-id: 25050d4ba28d25da226a7bc49d5b542947d0c512

Reviewed By: lbrandy

Differential Revision: D3964328

fbshipit-source-id: 0b1dc2d4b2a1565019770668445a624625b8257e

Summary:
This diff adds BatchDispatcher, which can be used to batch values while performing IO.
This would be useful in writing single id code in node, and would be use to batch ids while doing IO at storage adapter.

Differential Revision: D3900404

fbshipit-source-id: f53aa352344ff55674c7544302b6a1b4726214b6