Optimize writeNext Method

[tmdgusya]

Current writeNext function have unnecessary map method.
It cause unnecessary memory usage.

  private fun writeNext(row: List<Any?>) {
      val rowStr = row.map { field ->
          if (field == null) {
              ctx.nullCode
          } else {
              attachQuote(field.toString())
          }
      }.joinToString(ctx.delimiter.toString())
      writer.print(rowStr)
  }

Performance test

Result : Java Heap Space out error

---

Remove unnecessary map method.

  private fun writeNext(row: List<Any?>) {
      val rowStr = row.joinToString(ctx.delimiter.toString()) { field ->
          if (field == null) {
              ctx.nullCode
          } else {
              attachQuote(field.toString())
          }
      }
      writer.print(rowStr)
  }

Performance test

The test code was excluded for fear of slow execution for test.
If you want to measure performance test, the performance test must be isolate alone. Because of, All tests execute independently and pararell then they use some memory. So, it might be on unexpected result

---

TEST CODE

"does not throw java heap space exception when execute writeRows" {
    val rows = mutableListOf<String>()

    for (i in 0..100000000) {
        rows.add(i.toString())
    }

    val sequence = listOf<List<String>>(rows).asSequence()

    assertDoesNotThrow {
        csvWriter().open(testFileName) {
            writeRows(sequence)
        }
    }
}

[tmdgusya]

In the past, an error occurred when processing 10 million data, but now 100 million data can be processed.

[tmdgusya]

Before fixed it

---

After fixed it

[doyaaaaaken]

released in v1.5.0 🚀