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Fix marshalling of bool flags in MF #3210

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Merged
merged 3 commits into from
Apr 5, 2019
Merged

Fix marshalling of bool flags in MF #3210

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2c8090c
Fix marshalling of bool flags in MF
wschin Apr 5, 2019
fbbc121
Address comment
wschin Apr 5, 2019
1bcdc54
Better type of C# and C bool bridge
wschin Apr 5, 2019
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16 changes: 8 additions & 8 deletions src/Microsoft.ML.Recommender/SafeTrainingAndModelBuffer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -133,19 +133,19 @@ private struct MFParameter
/// Specify if the factor matrices should be non-negative.
/// </summary>
[FieldOffset(48)]
public int DoNmf;
public byte DoNmf;
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@eerhardt eerhardt Apr 5, 2019 •
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While this is better than what we had before, this is still not correct.

https://docs.microsoft.com/en-us/cpp/cpp/fundamental-types-cpp?view=vs-2019

bool Type bool is an integral type that can have one of the two values true or false. Its size is unspecified.

https://en.cppreference.com/w/cpp/language/types

bool - type, capable of holding one of the two values: true or false. The value of sizeof(bool) is implementation defined and might differ from 1.

Instead, to make interop/marshalling work correctly on all computers - the technique we use in .NET is to ensure the ABI (application binary interface) is stable no matter the compiler/processor/etc. This means only stable-sized types can be used in the ABI that C# code P/Invokes into.

So to fix this, the libmf C code should change to have a stable ABI. I see it uses float, int, and bool. For sure int and bool can change sizes depending on the compiler/processor. Instead, we should be using int32_t and int8_t on the C side. (Note: you can just have a wrapper export function in the C library that exposes the stable ABI and calls into your current code. So the main C/C++ code can remain unchanged.) #Closed

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Thank you for pointing this out. Another iteration is pushed. Hopefully, it can address this comment.


/// <summary>
/// Set to true so that LIBMF may produce less information to STDOUT.
/// </summary>
[FieldOffset(52)]
public int Quiet;
[FieldOffset(49)]
public byte Quiet;

/// <summary>
/// Set to false so that LIBMF may reuse and modifiy the data passed in.
/// </summary>
[FieldOffset(56)]
public int CopyData;
[FieldOffset(50)]
public byte CopyData;
}

[StructLayout(LayoutKind.Explicit)]
Expand Down Expand Up @@ -223,9 +223,9 @@ public SafeTrainingAndModelBuffer(IHostEnvironment env, int fun, int k, int nrTh
_mfParam.Eta = (float)eta;
_mfParam.Alpha = (float)alpha;
_mfParam.C = (float)c;
_mfParam.DoNmf = doNmf ? 1 : 0;
_mfParam.Quiet = quiet ? 1 : 0;
_mfParam.CopyData = copyData ? 1 : 0;
_mfParam.DoNmf = doNmf ? (byte)1 : (byte)0;
_mfParam.Quiet = quiet ? (byte)1 : (byte)0;
_mfParam.CopyData = copyData ? (byte)1 : (byte)0;
}

~SafeTrainingAndModelBuffer()
Expand Down
37 changes: 30 additions & 7 deletions src/Native/MatrixFactorizationNative/UnmanagedMemory.cpp
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Expand Up @@ -9,25 +9,48 @@

using namespace mf;

mf_parameter make_param(const mf_parameter_bridge *param_bridge)
{
mf_parameter param;
param.fun = param_bridge->fun;
param.k = param_bridge->k;
param.nr_threads = param_bridge->nr_threads;
param.nr_bins = param_bridge->nr_bins;
param.nr_iters = param_bridge->nr_iters;
param.lambda_p1 = param_bridge->lambda_p1;
param.lambda_p2 = param_bridge->lambda_p2;
param.lambda_q1 = param_bridge->lambda_q1;
param.lambda_q2 = param_bridge->lambda_q2;
param.eta = param_bridge->eta;
param.alpha = param_bridge->alpha;
param.c = param_bridge->c;
param.do_nmf = param_bridge->do_nmf != 0 ? true : false;
param.quiet = param_bridge->quiet != 0 ? true : false;
param.copy_data = param_bridge->copy_data != 0 ? true : false;
return param;
}

EXPORT_API(void) MFDestroyModel(mf_model *&model)
{
return mf_destroy_model(&model);
}

EXPORT_API(mf_model*) MFTrain(const mf_problem *prob, const mf_parameter *param)
EXPORT_API(mf_model*) MFTrain(const mf_problem *prob, const mf_parameter_bridge *param_bridge)
{
return mf_train(prob, *param);
auto param = make_param(param_bridge);
return mf_train(prob, param);
}

EXPORT_API(mf_model*) MFTrainWithValidation(const mf_problem *tr, const mf_problem *va, const mf_parameter *param)
EXPORT_API(mf_model*) MFTrainWithValidation(const mf_problem *tr, const mf_problem *va, const mf_parameter_bridge *param_bridge)
{
return mf_train_with_validation(tr, va, *param);
auto param = make_param(param_bridge);
return mf_train_with_validation(tr, va, param);
}


EXPORT_API(float) MFCrossValidation(const mf_problem *prob, int nr_folds, const mf_parameter *param)
EXPORT_API(float) MFCrossValidation(const mf_problem *prob, int nr_folds, const mf_parameter_bridge *param_bridge)
{
return mf_cross_validation(prob, nr_folds, *param);
auto param = make_param(param_bridge);
return mf_cross_validation(prob, nr_folds, param);
}

EXPORT_API(float) MFPredict(const mf_model *model, int p_idx, int q_idx)
Expand Down
25 changes: 22 additions & 3 deletions src/Native/MatrixFactorizationNative/UnmanagedMemory.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8,12 +8,31 @@

using namespace mf;

struct mf_parameter_bridge
{
int32_t fun;
int32_t k;
int32_t nr_threads;
int32_t nr_bins;
int32_t nr_iters;
float lambda_p1;
float lambda_p2;
float lambda_q1;
float lambda_q2;
float eta;
float alpha;
float c;
uint8_t do_nmf;
uint8_t quiet;
uint8_t copy_data;
};

EXPORT_API(void) MFDestroyModel(mf_model *&model);

EXPORT_API(mf_model*) MFTrain(const mf_problem *prob, const mf_parameter *param);
EXPORT_API(mf_model*) MFTrain(const mf_problem *prob, const mf_parameter_bridge *parameter_bridge);

EXPORT_API(mf_model*) MFTrainWithValidation(const mf_problem *tr, const mf_problem *va, const mf_parameter *param);
EXPORT_API(mf_model*) MFTrainWithValidation(const mf_problem *tr, const mf_problem *va, const mf_parameter_bridge *parameter_bridge);

EXPORT_API(float) MFCrossValidation(const mf_problem *prob, int nr_folds, const mf_parameter* param);
EXPORT_API(float) MFCrossValidation(const mf_problem *prob, int nr_folds, const mf_parameter_bridge* parameter_bridge);

EXPORT_API(float) MFPredict(const mf_model *model, int p_idx, int q_idx);
2 changes: 1 addition & 1 deletion src/Native/MatrixFactorizationNative/libmf
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Submodule libmf updated 1 files
+5 −0 mf.cpp