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[Timer] unresolved external symbol boost::chrono::time_point
by Aman Wardak 17 Feb '16

17 Feb '16

Env: Win7 32-bit running in VirtualBox on Macbook Pro Compiler: MS Visual Studio 14 It's my first time working with Boost. I've followed the instructions here: http://www.boost.org/doc/libs/1_60_0/more/getting_started/windows.html I've compiled Boost successfully: ============================ The Boost C++ Libraries were successfully built! The following directory should be added to compiler include paths: C:\Users\IEUser\Documents\boost_1_60_0 The following directory should be added to linker library paths: C:\Users\IEUser\Documents\boost_1_60_0\stage\lib ============================================== I've added the above paths in Visual Studio and was able to run the test in step 6 of the instructions linked above to verify my environment is set up correctly. MY PROBLEM: I'm trying to compile the very first sample code at this link: http://www.boost.org/doc/libs/1_60_0/libs/timer/doc/cpu_timers.html I get the following error: ------ Build started: Project: BoostExample, Configuration: Debug Win32 ------ Source.cpp libboost_timer-vc140-mt-gd-1_60.lib(cpu_timer.obj) : error LNK2019: unresolved external symbol "public: static class boost::chrono::time_point<class boost::chrono::steady_clock,class boost::chrono::duration<__int64,class boost::ratio<1,1000000000> > > __cdecl boost::chrono::steady_clock::now(void)" (?now@steady_clock @chrono@boost@@SA?AV?$time_point@Vsteady_clock@chrono@boost@@V?$duration@ _JV?$ratio@$00$0DLJKMKAA@@boost@@@23@@23@XZ) referenced in function __catch$??1auto_cpu_timer@timer@boost@@QAE@XZ$0 C:\Users\IEUser\Documents\Visual Studio 2015\Projects\CS2370\Debug\BoostExample.exe : fatal error LNK1120: 1 unresolved externals ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== Thanks, Aman

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[Test] BOOST_CHECK_EXCEPTION error message still vague
by Merrill Cornish 17 Feb '16

17 Feb '16

In BOOST_1_59_0, I complained that the error message from BOOST_CHECK_EXCEPTION was indecipherable. In BOOST_1_60_0, things improved a lot. But it still leave you hanging. I use the function fail_msg() as the predicate argument to BOOST_CHECK_EXCEPTION. If it finds a specified substring in the exception message, it returns true. Otherwise, it returns false. Below is an error message from BOOST_CHECK_EXCEPTION when the predicate returned false: exception "std::runtime_error" raised as expected: validation on the raised exception through predicate "fail_msg" The first clause says my code raised the expected exception class. That part of the message is clear and unambiguous. The second clause, however, is a non-sequitur. It seems to only acknowledge that there was a predicate named "fail_msg" without saying whether it returned true or false. Overall, the whole message doesn't say whether BOOST_CHECK_EXCEPTION passed or failed. Since a message was output, the user can assume things did not go well, but it seems like the message could be more explicit. Merrill Cornish

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multiprecision max and et_on
by Daniel Brake 16 Feb '16

16 Feb '16

Hi Boost, I would like to be able to use the Eigen linear algebra library with Boost.Multiprecision with et_on. However, as noted here: https://svn.boost.org/trac/boost/ticket/11149 for max, et_on isn't compatible out of the box. Aside from writing my own little overload for max for the particular form being produced in my line of code from within Eigen, does anyone have a fix for enabling max with expression templates on? MWE: { using mpfr = boost::multiprecision::mpfr_float; // et_on by default, which is what i want using std::max; mpfr a(1), b(2), c(4); auto q = b*b+c; mpfr r = max(a,q); } Thanks a lot, Daniel

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[GIL] Why doesn't pixel assignment color-convert?
by Stonewall Ballard 16 Feb '16

16 Feb '16

I've just started using boost.gil, though I've been looking at it for a while. It seems odd to me that assignment doesn't do an implicit color_convert() when the pixels are of different types. Instead, it just copies matching channels. That's the wrong thing to do when assigning an rgba pixel to an rgb pixel, since the former is straight and the latter is premultiplied. It also seems wrong that you can assign an rgba pixel to an rgb pixel, but not vice-versa. It looks like this is caused by pixels_are_compatible in gil_concept.hpp, where it fails to check that both pixels have the same number of channels. Instead, it matches channels of the output pixel against the input pixel, ignoring any extra input pixel channels. It also ignores scoped_channel_value usage. This seems like an error waiting to happen. Comments? - Stoney

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ASIO: add work and remove immed., will ignore further handler_requests???
by aj neu 16 Feb '16

16 Feb '16

Hi, below is some code where boost::asio::io_service::work is added, and then immediately removed. After that, I call async_wait on a steady_timer, but it does not work: io.run() RETURNS IMMEDIATELY, and IGNORES the async_wait. Is this intended? (I was rather surprised, because I thought that the async_wait would schedule new work, but it does not work). If I cange the code-line #define WEIRD_BEHAVIOUR to #undef WEIRD_BEHAVIOUR then I have my expected behaviour. Thanks, ajneu #include <iostream> #include <chrono> #include <experimental/optional> #include <boost/asio.hpp> #include <boost/asio/steady_timer.hpp> #define WEIRD_BEHAVIOUR int main() { boost::asio::io_service io; std::experimental::optional<boost::asio::io_service::work> work; #ifdef WEIRD_BEHAVIOUR work.emplace(io); work = std::experimental::nullopt; #endif boost::asio::steady_timer timer(io, std::chrono::milliseconds{1000}); timer.async_wait([](const boost::system::error_code &ec) { std::cout << ((!ec) ? "done" : "err") << std::endl; }); io.run(); }

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Writing a stratum client using boost:asio
by Jan Willem Penterman 11 Feb '16

11 Feb '16

Hi, I'm trying to write a stratum client for a cryptocurrency mining application. The mining application connects to a stratum server to receive new work to mine on and submit solutions. The stratum protocol is a simple TCP based line protocol with JSON payload. Documentation here: https://mining.bitcoin.cz/help/#!/manual/stratum-protocol I've chosen to use boost::asio, as boost is already heavily used in the fork of the project I'm building the miner for. But I'm having difficulties to understand why my current implementation doesn't work. The basic flow is as follows: 1. connect to the server. this works 2. send subscribe method. this also works 3. authorize worker(s). doesn't work. 4. stratum server should start pushing new work periodically. doesn't work. 5. submit solution when found. not implemented yet. Without authorization, the server should still start pushing work. So I've skipped step 3 for now. The source code as I have it now is available here: https://github.com/Genoil/cpp-ethereum/blob/stratum/libstratum/ The output I get from this is as follows: i 12:19:14|<unknown> Connected to stratum server coinotron.com : 3344 i 12:19:15|<unknown> {"error": null, "id": 1, "result": [["mining.notify", "91d0025c5ea54509977e3475d065169e"], "080016D0", 4]} i 12:19:15|<unknown> Subscribed i 12:19:15|<unknown> { "id": null, "method": "mining.set_difficulty", "params": [32768]} i 12:19:15|<unknown> mining.set_difficulty i 12:19:15|<unknown> {"params": ["31065", "0xc09361c52e9dddd141040cc79c52eaed382e92c1dd350324c040482a4c4ac0fa","0x5a46dd85298b0beff65ccf3006c4b5d2f7fa6ca8a5885a7f2132714fe7a48602","0x0000000200000000000000000000000000000000000000000000000000000000", true], "id": null, "method": "mining.notify"} i 12:19:15|<unknown> mining.notify >From this I can conclude that the subscription call works. Then at the end of handleResponse, I simply queue up a new async_read_until to wait for the next line of JSON to come in from the server. This also kind of works, but the idea is that after a few seconds, new work should come in as a "mining.notify". This never happens. Can anybody explain what I'm doing wrong? Regarding the mining.authorize call on line 113. I've understood from the documentation that I can send that whenever I want, so I tried to do this immediately after the subscribe method returned. But if I do this, it a) doesn't return and b) all lines after "Subscribed" don't come in any longer. This is the second problem I'm trying to figure out. I'm using this as reference, but my Python is even worse than my C++ https://github.com/slush0/stratum-mining-proxy But when I run the binaries connecting to the same host (coinotron.com:3344), I do get new work coming in... Thanks for having a look at this.

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[ASIO] Newbie question - Bidirectional communication example
by Davies, John 11 Feb '16

11 Feb '16

For a simple explanation I have two processes that run on the same computer. Process 1 sends messages to Process 2 by putting the messages into an Interprocess message queue that Process 2 created. Process 2 sends messages to Process 1 by putting the messages into an Interprocess message queue that Process 1 created. The messages can be sent at any time and are not in response to each other. Very symmetrical. Now I want to put Process 1 and Process 2 on separate computers. My intent is to transfer the messages over TCP to the opposite computer without changing Process 1 or 2. So I thought I'd create two connector programs. Connector 1 creates a message queue that pretends to be the Process 2 message queue. When it gets a message, it send it over TCP the Connector 2. Connector 2 gets the message and puts it into the real Process 2 message queue. And the reverse if Process 2 has an outgoing message. I just can't find a good example to steal from. Everything I can find are more like Process 1 makes a request and Process 2 responds. So I think I have a fundamental misunderstanding of how ASIO works. ________________________________ The information contained in this message may be confidential and legally protected under applicable law. The message is intended solely for the addressee(s). If you are not the intended recipient, you are hereby notified that any use, forwarding, dissemination, or reproduction of this message is strictly prohibited and may be unlawful. If you are not the intended recipient, please contact the sender by return e-mail and destroy all copies of the original message.

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[Test] Funny Business with vector::at() out-of-range
by Merrill Cornish 11 Feb '16

11 Feb '16

I posted a question a couple of days ago: "Throws 'Escaping' both BOOST_CHECK_THROW and try{}". I found that BOOST_CHECK_EXCEPTION which is working for me elsewhere fails the same way. So, an out-of-range std::vector::at() seems to be the common element. In the definition of at(), the out-of-range response is handled by __throw_out_of_range_fmt(). When I looked up that one, I found void __throw_out_of_range_fmt(const char*, ...) __attribute__((__noreturn__)) __attribute__((__format__(__gnu_printf__, 1, 2))); in functexcept.h. To my admittedly less-than-expert eye, there doesn't seem to be an actual throw() here. On the other hand, the entire file are entries like this for various exceptions. There are a lot of Google hits for __throw_out_of_range_fmt, but they are for unresolved references in links, apparently caused by mixed version of libraries and object. Everything I've got is compiled linked for MinGW 64-bit, GCC 5.3.0, 64-bit --std=C++14, BOOST 1_60_1 64-bit so I get none of those errors. The problem I'm seeing with my test code is that wrapping a try{} around BOOST_CHECK_THROW shows that [1] the body of the try doesn't complete; but at the same time [2] not even a catch(...) can catch the presumed throw--as if a throw isn't actually being done. So, where did the throw go? Merrill Cornish

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[TEST] Throws "Escaping" both BOOST_CHECK_THROW and try{}
by Merrill Cornish 11 Feb '16

11 Feb '16

I'm running Windows 10, 64-bit; MinGW 64-bit; GCC 5.3 64-bit; and BOOST 1_60_1 Here is the relevant test code: [319] BOOST_CHECK_THROW(throw std::out_of_range("BOOST_CK_THROW test"), std::out_of_range); [320] try { [321] std::cerr << "arcsSize()" << std::endl; [322] empty1.arcsSize(Operand::DEFAULT_ARC_SET+1); [323] std::cerr << "arcsSize() did not throw" << std::endl; [324] }//try [325] catch (const std::out_of_range& ex) [326] { std::cerr << "out_of_range caught=|" << ex.what() << "|" << std::endl; } [327] catch (...) { std::cerr << "something else caught" << std::endl; } [328] [329] BOOST_CHECK_THROW(empty1.arcsSize(Operand::DEFAULT_ARC_SET+1), std::out_of_range); The original code was just the last line, line [329]. [319]-[327] was added in an attempt to characterize the problem. The error [329] got by itself was: terminate called after throwing an instance of 'std::out_of_range' what(): vector::_M_range_check: __n (which is 1) >= this->size() (which is 1) This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. SIGABRT intercepted; converted to exit(EXIT_FAILURE). arcSize() is implemented with std::vector::at() and the index is out-of-range, so it's supposed to throw std::out_of_range. That's what was detected, so why did it terminate the program? (The last line comes from my SIGABRT handler. Without it, the test executable ends up locked and can't be deleted.) Adding in all of the test lines shown above gives; [319] Operand_Test.cpp(319): info: check 'exception "std::out_of_range" raised as expected' has passed [321] arcsSize() terminate called after throwing an instance of 'std::out_of_range' what(): vector::_M_range_check: __n (which is 1) >= this->size() (which is 1) This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. SIGABRT intercepted; converted to exit(EXIT_FAILURE). Notice the explicit throw in line [319] is detected and handled properly. However, the arcSize() call from inside the try block throws, but is not caught by even catch(...) {}. Can anyone help me see what's going on here? Merrill Cornish

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[Container] Regarding Trac #11957, static_vector::max_size() is higher than the capacity
by Gagan Kumar 10 Feb '16

10 Feb '16

I tried a simple fix for https://svn.boost.org/trac/boost/ticket/11957 here https://github.com/boostorg/container/pull/37/files . Can someone please review it. Regards,Gagan Kumar

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