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TweetParser.cpp
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TweetParser.cpp
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/* Copyright 2013 Vertica, an HP Company */
#include "Vertica.h"
using namespace Vertica;
#include <string>
#include <sstream>
#include <iostream>
#include <json/json.h>
class TweetParser : public UDParser {
private:
const SizedColumnTypes returnType;
static const char NEWLINE = '\n';
bool hasRun;
std::vector< std::vector<std::string> > colNames;
RejectedRecord rr;
bool hasRejectedRecord;
// cast the result to the correct type for the column
void writeResult(Json::Value result, StreamWriter *writer, size_t column) {
VerticaType vtype = returnType.getColumnType(column);
const BaseDataOID typeOid = vtype.getTypeOid();
switch (typeOid) {
case Int8OID:
{
if (result.isUInt())
writer->setInt(column, result.asUInt64());
else if (result.isInt())
writer->setInt(column, result.asInt64());
else
writer->setNull(column);
break;
}
case Float8OID:
{
if (result.isDouble())
writer->setFloat(column, result.asDouble());
else
writer->setNull(column);
break;
}
case NumericOID:
{
if (result.isNumeric()) {
Vertica::VNumeric tmp = writer->getNumericRef(column);
tmp.copy(result.asDouble());
} else
writer->setNull(column);
break;
}
case TimestampTzOID:
{
if (result.isString()) {
TimestampTz tz = Vertica::timestamptzIn(result.asString().c_str(), -1, true);
writer->setTimestampTz(column, tz);
}
else
writer->setNull(column);
break;
}
case TimestampOID:
{
if (result.isString()) {
Timestamp t = Vertica::timestampIn(result.asString().c_str(), -1, true);
writer->setTimestamp(column, t);
}
else
writer->setNull(column);
break;
}
case CharOID:
case VarcharOID:
case VarbinaryOID:
case LongVarbinaryOID:
case LongVarcharOID:
{
if (result.isString()) {
Vertica::VString tmp = writer->getStringRef(column);
tmp.copy(result.asString());
} else
writer->setNull(column);
break;
}
default:
writer->setNull(column);
}
}
// populate the table for this input row
bool parseTweet(std::string input, StreamWriter *writer) {
Json::Reader reader;
Json::Value result;
if (!reader.parse(input, result))
return false;
std::ostringstream defName;
// find the result for each column
for (size_t j = 0; j < colNames.size(); j++) {
std::vector<std::string> colParts = colNames[j];
Json::Value resultCopy = result;
bool isMember = true;
// iterate through the column name components
// Ex: "coordinates.coordinates.0" would have colParts=["coordinates", "coordinates", 0]
for (size_t k = 0; k < colParts.size(); k++) {
// non-scalar -- array lookup
if (colParts[k].find_first_not_of("0123456789") == std::string::npos)
{
std::stringstream ss (colParts[k]);
int index;
ss >> index;
if (resultCopy.isArray() && resultCopy.isValidIndex(index))
resultCopy = resultCopy[index];
else {
isMember = false;
break;
}
}
// scalar -- direct lookup
else {
if (resultCopy.isArray() || !resultCopy.isMember(colParts[k])) {
isMember = false;
break;
}
resultCopy = resultCopy.get(colParts[k], defName.str());
}
}
// this column name was not in the record. set the column value to null
if (!isMember)
writer->setNull(j);
// found it, write the result
else {
writeResult(resultCopy, writer, j);
}
}
return true;
}
void rejectRecord(std::string record, const std::string &reason) {
RejectedRecord rej(reason, record.c_str(), record.length(),
std::string(1, '\n'));
rr = rej;
}
public:
TweetParser(const SizedColumnTypes &returnType) : returnType(returnType) {
for (size_t i = 0; i < returnType.getColumnCount(); i++) {
std::vector<std::string> colParts;
std::istringstream colName(returnType.getColumnName(i));
// tokenize the column name by periods in order to iterate through the Json::Value objects later
std::string s;
while (std::getline(colName, s, '.')) {
colParts.push_back(s);
}
colNames.push_back(colParts);
}
hasRejectedRecord = false;
}
virtual StreamState process(ServerInterface &srvInterface, DataBuffer &input, InputState input_state)
{
VIAssert(hasRun || input.size >= 65000 || input_state == END_OF_FILE); // VER-22560
hasRun = true;
char * input_buf = (char*)input.buf;
size_t last_newline_index = 0;
size_t i;
for (i = input.offset; i < input.size; i++) {
if (input_buf[i] == NEWLINE && i != 0) {
if (last_newline_index != i - 1) {
// Copy to a std::string, to get null termination
std::string str(&input_buf[last_newline_index], &input_buf[i]);
if (parseTweet(str, writer))
writer->next();
else {
rejectRecord(str, "Parsing error. Possibly due to a malformed tweet.");
hasRejectedRecord = false;
input.offset = i;
return REJECT;
}
}
last_newline_index = i;
}
}
if (input_state == END_OF_FILE) {
// Special case:
// If we see "12\n34\n5" in a block, we want to stop after "12\n34\n"
// because the next block might contain "6\n78" and we don't want to
// mis-parse the "56" as a "5" and a "6". (Blocks can split the data
// stream between any arbitrary two bytes; we have no guarantee of
// a useful or convenient split there.)
// However, if "12\n34\n5" is the last block of the file, then
// we know that there's no following 6 and most likely the user just
// didn't give us a trailing newline.
// In that case, parse the "5" as a number.
if (input.size > 0 && last_newline_index != i) {
std::string str(&input_buf[last_newline_index], &input_buf[i]);
parseTweet(str, writer);
}
input.offset = input.size;
return DONE;
} else {
input.offset = last_newline_index;
return INPUT_NEEDED;
}
}
/** Returns information about the rejected record */
Vertica::RejectedRecord getRejectedRecord() { return rr; }
};
class TweetParserFactory : public ParserFactory {
public:
virtual void plan(ServerInterface &srvInterface,
PerColumnParamReader &perColumnParamReader,
PlanContext &planCtxt) {
}
virtual UDParser* prepare(ServerInterface &srvInterface,
PerColumnParamReader &perColumnParamReader,
PlanContext &planCtxt,
const SizedColumnTypes &returnType) {
return vt_createFuncObj(srvInterface.allocator, TweetParser, returnType);
}
virtual void getParserReturnType(ServerInterface &srvInterface,
PerColumnParamReader &perColumnParamReader,
PlanContext &planCtxt,
const SizedColumnTypes &argTypes,
SizedColumnTypes &returnType) {
returnType = argTypes;
}
};
RegisterFactory(TweetParserFactory);