From 66ac52c5dba12224f65fc4dd4568ff49e959696c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Geoffrey=20=E2=80=9CFrogeye=E2=80=9D=20Preud=27homme?=
 <geoffrey@frogeye.fr>
Date: Mon, 9 Dec 2019 10:42:37 +0100
Subject: [PATCH] Workflow: JSON parser acceleration

Sadly is even worse because of the ctypes-induced conversions.
---
 accel.c     | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 feed_dns.py | 33 +++++++++++++++++----------
 2 files changed, 86 insertions(+), 13 deletions(-)

diff --git a/accel.c b/accel.c
index bda0072..72acc32 100644
--- a/accel.c
+++ b/accel.c
@@ -1,6 +1,7 @@
 #include <stdlib.h>
+#include <stdio.h>
 
-int ip4_flat(char* value, wchar_t* flat)
+char ip4_flat(char* value, wchar_t* flat)
 {
     unsigned char value_index = 0;
     unsigned char octet_index = 0;
@@ -35,3 +36,66 @@ int ip4_flat(char* value, wchar_t* flat)
     } while (1); // This ugly thing save one comparison
     return 1;
 }
+
+#define MAX_OUTPUT 255
+
+char feed_dns_parse_json(char* line, char* name, char* value)
+{
+    unsigned short line_index = 0;
+    unsigned char quote_index = 0;
+    unsigned char output_index = 0;
+    char line_chara;
+    char* current_output = NULL;
+    char type = 0; // 0: error, 1: cname, 2: a, 3: aaaa
+    do {
+        line_chara = line[line_index];
+        if (line_chara == '"') {
+            quote_index += 1;
+            switch (quote_index) {
+                case 7: // Start of name
+                    current_output = name;
+                    break;
+                case 8: // End of name
+                    name[output_index] = '\0';
+                    current_output = NULL;
+                    break;
+                case 11: // Start of type
+                    line_chara = line[++line_index];
+                    if (line_chara == 'c') { // Must be CNAME
+                        type = 1;
+                        break;
+                    } else if (line_chara == 'a') { // A or AAAA
+                        line_chara = line[++line_index];
+                        if (line[line_chara+2] == '"') { // Is A
+                            type = 2;
+                            quote_index++;
+                            break;
+                        } else if (line[line_chara+1] == 'a') { // Must be AAAA
+                            type = 3;
+                            break;
+                        }
+                    }
+                    return 0;
+                case 15: // Start of value
+                    current_output = value;
+                    break;
+                case 16: // End of value
+                    value[output_index] = '\0';
+                    return type;
+            }
+            output_index = 0;
+        } else if (line_chara == '\0') {
+            return 0;
+        } else {
+            if (current_output != 0) {
+                if (output_index >= MAX_OUTPUT) {
+                    return 0;
+                }
+                current_output[output_index] = line_chara;
+                output_index++;
+            }
+        }
+        line_index++;
+    } while (1); // This ugly thing save one comparison
+    return 0;
+}
diff --git a/feed_dns.py b/feed_dns.py
index 1cc3247..0505155 100755
--- a/feed_dns.py
+++ b/feed_dns.py
@@ -3,10 +3,16 @@
 import database
 import argparse
 import sys
+import ctypes
+import json
+
+ACCEL = ctypes.cdll.LoadLibrary('./libaccel.so')
+ACCEL_NAME_BUF = ctypes.create_string_buffer(b'Z'*255, 255)
+ACCEL_VALUE_BUF = ctypes.create_string_buffer(b'Z'*255, 255)
 
 FUNCTION_MAP = {
-        b'a': database.feed_a,
-        b'cname': database.feed_cname,
+    b'a': database.feed_a,
+    b'cname': database.feed_cname,
 }
 
 if __name__ == '__main__':
@@ -21,21 +27,24 @@ if __name__ == '__main__':
 
     database.open_db()
 
+    line = b'(none)'
+
+    def err(name: bytes, value: bytes) -> None:
+        print(f"Error with line: {line!r}")
+
+    FUNCTIONS = [err, database.feed_cname, database.feed_a]
+
     try:
         database.time_step('iowait')
-        line: bytes
         for line in args.input:
             database.time_step('feed_json_parse')
-            split = line.split(b'"')
-            name = split[7]
-            dtype = split[11]
-            value = split[15]
-            # data = json.loads(line)
-            # assert dtype == data['type']
-            # assert name == data['name']
-            # assert value == data['value']
+            dtype = ACCEL.feed_dns_parse_json(
+                ctypes.c_char_p(line),
+                ACCEL_NAME_BUF,
+                ACCEL_VALUE_BUF
+            )
             database.time_step('feed_switch')
-            FUNCTION_MAP[dtype](name, value)
+            FUNCTIONS[dtype](ACCEL_NAME_BUF.value, ACCEL_VALUE_BUF.value)
             database.time_step('iowait')
     except KeyboardInterrupt:
         print("Interupted.")