westonpace commented on a change in pull request #12537:
URL: https://github.com/apache/arrow/pull/12537#discussion_r817330103
##########
File path: cpp/src/arrow/compute/exec/tpch_node.cc
##########
@@ -0,0 +1,3738 @@
+#include "arrow/compute/exec/tpch_node.h"
+#include "arrow/util/make_unique.h"
+#include "arrow/util/future.h"
+#include "arrow/util/unreachable.h"
+
+#include <algorithm>
+#include <bitset>
+#include <cstring>
+#include <random>
+#include <vector>
+#include <memory>
+#include <mutex>
+#include <queue>
+#include <unordered_set>
+
+namespace arrow
+{
+ using internal::checked_cast;
+
+ namespace compute
+ {
+ class TpchText
+ {
+ public:
+ Status Init();
+ Result<Datum> GenerateComments(
+ size_t num_comments,
+ size_t min_length,
+ size_t max_length,
+ random::pcg32_fast &rng);
+
+ private:
+ void GenerateWord(size_t &offset, const char **words, size_t
num_choices);
+ void GenerateNoun(size_t &offset);
+ void GenerateVerb(size_t &offset);
+ void GenerateAdjective(size_t &offset);
+ void GenerateAdverb(size_t &offset);
+ void GeneratePreposition(size_t &offset);
+ void GenerateAuxiliary(size_t &offset);
+ void GenerateTerminator(size_t &offset);
+
+ void GenerateNounPhrase(size_t &offset);
+ void GenerateVerbPhrase(size_t &offset);
+ void GeneratePrepositionalPhrase(size_t &offset);
+
+ void GenerateSentence(size_t &offset);
+
+ std::unique_ptr<Buffer> text_;
+ random::pcg32_fast rng_;
+ static constexpr size_t kTextBytes = 300 * 1024 * 1024; // 300 MB
+ };
+
+ class TpchTableGenerator
+ {
+ public:
+ using OutputBatchCallback = std::function<void(ExecBatch)>;
+ using FinishedCallback = std::function<void(int64_t)>;
+ using GenerateFn = std::function<Status(size_t)>;
+ using ScheduleCallback = std::function<Status(GenerateFn)>;
+ using AbortCallback = std::function<void()>;
+
+ virtual Status Init(
+ std::vector<std::string> columns,
+ int scale_factor,
+ int64_t batch_size) = 0;
+
+ virtual Status StartProducing(
+ size_t num_threads,
+ OutputBatchCallback output_callback,
+ FinishedCallback finished_callback,
+ ScheduleCallback schedule_callback) = 0;
+
+ void Abort(AbortCallback abort_callback)
+ {
+ bool expected = false;
+ if(done_.compare_exchange_strong(expected, true))
+ {
+ abort_callback();
+ }
+ }
+
+ virtual std::shared_ptr<Schema> schema() const = 0;
+
+ virtual ~TpchTableGenerator() = default;
+
+ protected:
+ std::atomic<bool> done_ = { false };
+ std::atomic<int64_t> batches_generated_ = { 0 };
+ };
+
+ int GetNumDigits(int64_t x)
+ {
+ // This if statement chain is for MAXIMUM SPEED
+ /*
+ .,
+ . _,'f----.._
+ |\ ,-'"/ | ,'
+ |,_ ,--. /
+ /,-. ,'`. (_
+ f o| o|__ "`-.
+ ,-._.,--'_ `. _.,-`
+ `"' ___.,'` j,-'
+ `-.__.,--'
+ */
+ // Source:
https://stackoverflow.com/questions/1068849/how-do-i-determine-the-number-of-digits-of-an-integer-in-c
Review comment:
Modification doesn't really matter from a legal perspective. Derivative
works are only allowed if you have rights to the source.
That being said, we are in a terrible gray area here that I fear will become
a can of worms and a waste of everyone's time. Technically the only "proper"
approach would be a [clean room
approach](https://en.wikipedia.org/wiki/Clean_room_design) where @save-buffer
describes what is needed to someone that has never seen the SO code and that
person writes the code. However, legally documenting such a process is a
headache.
In this case I think we are (at least ethically) in the clear. The answer
author has this statement on their profile page:
> All code I post on Stack Overflow is covered by the "Do whatever the heck
you want with it" licence, the full text of which is:
>
> Do whatever the heck you want with it.
>
There are a few edits by other authors but none of which touches the code
included here. My opinion would be to proceed as is (but get rid of the ASCII
art, I can't abide fun).
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