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Merged
jackgerrits merged 2 commits into from
Jun 10, 2021
Merged

feat: add cache helper for reading and writing types directly #3057

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b1a1a32
feat: add cache helper for reading and writing types directly
jackgerrits Jun 9, 2021
924af29
Merge branch 'master' into jagerrit/cache_templated_read
jackgerrits Jun 9, 2021
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29 changes: 9 additions & 20 deletions vowpalwabbit/cache.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -71,25 +71,19 @@ int read_cached_features(vw* all, v_array<example*>& examples)
all->example_parser->_shared_data, &ae->l, ae->_reduction_features, *input);
if (total == 0) return 0;
if (read_cached_tag(*input, ae) == 0) return 0;
char* c;

// is newline example or not
unsigned char newline_indicator = 0;
if (input->buf_read(c, sizeof(newline_indicator)) < sizeof(newline_indicator)) return 0;
newline_indicator = *reinterpret_cast<unsigned char*>(c);
unsigned char newline_indicator = input->read_value<unsigned char>("newline_indicator");
if (newline_indicator == newline_example) { ae->is_newline = true; }
else
{
ae->is_newline = false;
}
c += sizeof(newline_indicator);
all->example_parser->input->set(c);

// read indices
unsigned char num_indices = 0;
if (input->buf_read(c, sizeof(num_indices)) < sizeof(num_indices)) return 0;
num_indices = *reinterpret_cast<unsigned char*>(c);
c += sizeof(num_indices);
unsigned char num_indices = input->read_value<unsigned char>("num_indices");

all->example_parser->input->set(c);
char* c;
for (; num_indices > 0; num_indices--)
{
size_t temp;
Expand All @@ -107,7 +101,7 @@ int read_cached_features(vw* all, v_array<example*>& examples)
features& ours = ae->feature_space[index];
size_t storage = *reinterpret_cast<size_t*>(c);
c += sizeof(size_t);
all->example_parser->input->set(c);
input->set(c);
total += storage;
if (input->buf_read(c, storage) < storage)
{
Expand Down Expand Up @@ -138,7 +132,7 @@ int read_cached_features(vw* all, v_array<example*>& examples)
last = i;
ours.push_back(v, i);
}
all->example_parser->input->set(c);
input->set(c);
}

return static_cast<int>(total);
Expand Down Expand Up @@ -212,13 +206,8 @@ void cache_features(io_buf& cache, example* ae, uint64_t mask)
{
cache_tag(cache, ae->tag);

if (ae->is_newline) { output_byte(cache, newline_example); }
else
{
output_byte(cache, non_newline_example);
}
output_byte(cache, static_cast<unsigned char>(ae->indices.size()));

cache.write_value<unsigned char>(ae->is_newline ? newline_example : non_newline_example);
cache.write_value<unsigned char>(static_cast<unsigned char>(ae->indices.size()));
for (namespace_index ns : ae->indices) output_features(cache, ns, ae->feature_space[ns], mask);
}

Expand Down
32 changes: 31 additions & 1 deletion vowpalwabbit/io_buf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -189,7 +189,7 @@ class io_buf
size_t unflushed_bytes_count() { return head - _buffer._begin; }

void flush();

bool close_file()
{
if (!input_files.empty())
Expand All @@ -212,6 +212,36 @@ class io_buf
while (close_file()) {}
}

template <typename T>
void write_value(const T& value)
{
char* c;
buf_write(c, sizeof(T));
*reinterpret_cast<T*>(c) = value;
c += sizeof(T);
set(c);
}

template <typename T>
T read_value(const char* debug_name = nullptr)
{
char* c;
T value;
if (buf_read(c, sizeof(T)) < sizeof(T))
{
if (debug_name != nullptr)
{ THROW("Failed to read cache value: " << debug_name << ", with size: " << sizeof(T)); }
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@lokitoth lokitoth Jun 9, 2021

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This is probably out of scope for this change, but does it make sense to have a mode where an error in reading from the cache would cause the learning to switch back to reading from non-cache? Or is the coordination hard enough to make it not worth the time?

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@jackgerrits jackgerrits Jun 9, 2021

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In the current landscape the coordination to achieve that is hard enough to not make it worth it. I can see it being a nice thing to have in future though.

else
{
THROW("Failed to read cache value with size: " << sizeof(T));
}
}
value = *reinterpret_cast<T*>(c);
c += sizeof(T);
set(c);
return value;
}

void buf_write(char*& pointer, size_t n);
size_t buf_read(char*& pointer, size_t n);

Expand Down