LSTMTrainer: Catch empty vectors

[stweil]

The new test in LSTMTrainer::UpdateErrorGraph fixes an assertion
(see issues #644, #792).

The new test in LSTMTrainer::ReadTrainingDump was added to improve
the robustness of the code.

Signed-off-by: Stefan Weil [email protected]

[Shreeshrii]

I am still getting the error as this is not merged yet.

Breakpoint 7, tesseract::LSTMTrainer::ReadSizedTrainingDump (this=this@entry=0x7f2a7cb9f680, data=0x0, size=0) at lstmtrainer.cpp:924
924     bool LSTMTrainer::ReadSizedTrainingDump(const char* data, int size) {
(gdb) backtrace
#0  tesseract::LSTMTrainer::ReadSizedTrainingDump (this=this@entry=0x7f2a7cb9f680, data=0x0, size=0) at lstmtrainer.cpp:924
#1  0x0000000000428cc1 in tesseract::LSTMTrainer::ReadTrainingDump (this=this@entry=0x7f2a7cb9f680, data=..., trainer=trainer@entry=0x7f2a7cb9f680)
    at lstmtrainer.cpp:921
#2  0x000000000040af96 in tesseract::LSTMTester::RunEvalSync (this=this@entry=0x7fffe865b310, iteration=1, training_errors=<optimized out>, model_data=...,
    training_stage=1) at lstmtester.cpp:86
#3  0x000000000040b476 in tesseract::LSTMTester::ThreadFunc (lstmtester_void=0x7fffe865b310) at lstmtester.cpp:123
#4  0x00007f2a82be8184 in start_thread (arg=0x7f2a7cba0700) at pthread_create.c:312
#5  0x00007f2a820ca37d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
(gdb) info frame
Stack level 0, frame at 0x7f2a7cb9f540:
 rip = 0x428c40 in tesseract::LSTMTrainer::ReadSizedTrainingDump (lstmtrainer.cpp:924); saved rip = 0x428cc1
 called by frame at 0x7f2a7cb9f540
 source language c++.
 Arglist at 0x7f2a7cb9f530, args: this=this@entry=0x7f2a7cb9f680, data=0x0, size=0
 Locals at 0x7f2a7cb9f530, Previous frame's sp is 0x7f2a7cb9f538
(gdb) up
#1  0x0000000000428cc1 in tesseract::LSTMTrainer::ReadTrainingDump (this=this@entry=0x7f2a7cb9f680, data=..., trainer=trainer@entry=0x7f2a7cb9f680)
    at lstmtrainer.cpp:921
921       return trainer->ReadSizedTrainingDump(&data[0], data.size());
(gdb) info frame
Stack level 1, frame at 0x7f2a7cb9f540:
 rip = 0x428cc1 in tesseract::LSTMTrainer::ReadTrainingDump (lstmtrainer.cpp:921); saved rip = 0x40b476
 tail call frame, caller of frame at 0x7f2a7cb9f540
 source language c++.
 Arglist at unknown address.
 Locals at unknown address, Previous frame's sp is 0x7f2a7cb9f540
(gdb) up
#2  0x000000000040af96 in tesseract::LSTMTester::RunEvalSync (this=this@entry=0x7fffe865b310, iteration=1, training_errors=<optimized out>, model_data=...,
    training_stage=1) at lstmtester.cpp:86
86        if (!trainer.ReadTrainingDump(model_data, &trainer)) {
(gdb) info frame
Stack level 2, frame at 0x7f2a7cb9feb0:
 rip = 0x40af96 in tesseract::LSTMTester::RunEvalSync (lstmtester.cpp:86); saved rip = 0x40b476
 called by frame at 0x7f2a7cb9fee0, caller of frame at 0x7f2a7cb9f540
 source language c++.
 Arglist at 0x7f2a7cb9f538, args: this=this@entry=0x7fffe865b310, iteration=1, training_errors=<optimized out>, model_data=..., training_stage=1
 Locals at 0x7f2a7cb9f538, Previous frame's sp is 0x7f2a7cb9feb0
 Saved registers:
  rbx at 0x7f2a7cb9fe78, rbp at 0x7f2a7cb9fe80, r12 at 0x7f2a7cb9fe88, r13 at 0x7f2a7cb9fe90, r14 at 0x7f2a7cb9fe98, r15 at 0x7f2a7cb9fea0, rip at 0x7f2a7cb9fea8
(gdb)

[stweil]

@zdenop, please merge before more people get this assertion.