jl777
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March 22, 2014, 10:36:43 PM |
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[JSON codec release]
Not following this thread has given me some extra time. I was in the process of changing the gateway_AM format and wanted to use JSON for sending requests to the gateway. However, with the 1000 byte limit of AM, cant really afford the JSON bloat. After searching a bit for an effective JSON compressor, I decided to just write a wrapper around zlib optimized for NXT. The following is the result. In my small number of tests, I am getting compression rates of 2:1 to 4:1, your mileage will vary. To use it, make sure to call init_jsoncodec(), if you send it a JSON string, it will do a test compress and decompress. After it is initialized, you can just call encode_json(char *jsontext) and it returns a pointer to the compressed data. To decompress, just pass that pointer to decode_json() and it will allocate space and return the JSON string. If you find any bugs PM me. It is supposed to be lossless after all whitespace is removed. That's it for now. Going back under. James struct compressed_json { uint32_t complen,sublen,origlen; unsigned char encoded[]; }; int init_jsoncodec(char *jsontext); struct compressed_json *encode_json(char *jsontext); char *decode_json(struct compressed_json *jsn); //
// jsoncodec.h
// Created by jl777, Mar 2014
// MIT License
//
#ifndef gateway_jsoncodec_h
#define gateway_jsoncodec_h
#include <zlib.h>
struct compressed_json { uint32_t complen,sublen,origlen; unsigned char encoded[]; };
struct jsonwords { char *word; int len,count; };
struct jsonwords *JSONlist = 0;
struct jsonwords _JSONlist[] = { {"requestType", 11, 2}, {"alias", 5, 5}, {"uri", 3, 3}, {"transactionBytes", 16, 3}, {"order", 5, 4}, {"poll", 4, 2}, {"vote", 4, 1}, {"name", 4, 4}, {"description", 11, 4}, {"minNumberOfOptions", 18, 2}, {"maxNumberOfOptions", 18, 2}, {"optionsAreBinary", 16, 2}, {"option", 6, 1}, {"secretPhrase", 12, 8}, {"publicKey", 9, 4}, {"deadline", 8, 3}, {"fee", 3, 1}, {"referencedTransaction", 21, 1}, {"hallmark", 8, 3}, {"website", 7, 2}, {"token", 5, 2}, {"account", 7, 15}, {"timestamp", 9, 7}, {"asset", 5, 11}, {"type", 4, 1}, {"subtype", 7, 1}, {"limit", 5, 2}, {"assetName", 9, 1}, {"block", 5, 2}, {"numberOfConfirmations", 21, 1}, {"peer", 4, 1}, {"firstIndex", 10, 1}, {"lastIndex", 9, 1}, {"transaction", 11, 4}, {"hash", 4, 4}, {"quantity", 8, 7}, {"host", 4, 3}, {"weight", 6, 3}, {"date", 4, 2}, {"price", 5, 4}, {"recipient", 9, 3}, {"message", 7, 1}, {"amount", 6, 1}, {"errorCode", 9, 10}, {"errorDescription", 16, 10}, {"error", 5, 3}, {"valid", 5, 2}, {"balance", 7, 3}, {"effectiveBalance", 16, 3}, {"unconfirmedBalance", 18, 3}, {"assetBalances", 13, 1}, {"unconfirmedAssetBalances", 24, 1}, {"blockIds", 8, 1}, {"askOrderIds", 11, 2}, {"bidOrderIds", 11, 2}, {"accountId", 9, 1}, {"transactionIds", 14, 1}, {"id", 2, 1}, {"aliasIds", 8, 1}, {"trades", 6, 2}, {"height", 6, 3}, {"numberOfTrades", 14, 2}, {"assetIds", 8, 1}, {"assets", 6, 1}, {"generator", 9, 1}, {"numberOfTransactions", 20, 2}, {"totalAmount", 11, 1}, {"totalFee", 8, 1}, {"payloadLength", 13, 1}, {"version", 7, 3}, {"baseTarget", 10, 1}, {"previousBlock", 13, 1}, {"nextBlock", 9, 1}, {"payloadHash", 11, 1}, {"generationSignature", 19, 1}, {"previousBlockHash", 17, 1}, {"blockSignature", 14, 1}, {"transactions", 12, 1}, {"genesisBlockId", 14, 1}, {"genesisAccountId", 16, 1}, {"maxBlockPayloadLength", 21, 1}, {"maxArbitraryMessageLength", 25, 1}, {"transactionTypes", 16, 1}, {"peerStates", 10, 1}, {"guaranteedBalance", 17, 2}, {"address", 7, 1}, {"state", 5, 1}, {"announcedAddress", 16, 1}, {"shareAddress", 12, 1}, {"downloadedVolume", 16, 1}, {"uploadedVolume", 14, 1}, {"application", 11, 1}, {"platform", 8, 1}, {"blacklisted", 11, 1}, {"peers", 5, 1}, {"options", 7, 1}, {"voters", 6, 1}, {"pollIds", 7, 1}, {"time", 4, 2}, {"lastBlock", 9, 1}, {"cumulativeDifficulty", 20, 1}, {"totalEffectiveBalance", 21, 1}, {"numberOfBlocks", 14, 1}, {"numberOfAccounts", 16, 1}, {"numberOfAssets", 14, 1}, {"numberOfOrders", 14, 1}, {"numberOfAliases", 15, 1}, {"numberOfPolls", 13, 1}, {"numberOfVotes", 13, 1}, {"numberOfPeers", 13, 1}, {"numberOfUsers", 13, 1}, {"numberOfUnlockedAccounts", 24, 1}, {"lastBlockchainFeeder", 20, 1}, {"availableProcessors", 19, 1}, {"maxMemory", 9, 1}, {"totalMemory", 11, 1}, {"freeMemory", 10, 1}, {"confirmations", 13, 2}, {"blockTimestamp", 14, 1}, {"sender", 6, 1}, {"unconfirmedTransactionIds", 25, 1}, {"aliases", 7, 1}, {"foundAndStopped", 15, 1}, };
int Num_JSONwords = 123;
int64_t stripstr(char *buf,int64_t len)
{
int i,j,c;
for (i=j=0; i<len; i++)
{
c = buf[i];
//if ( c == '\\' )
// c = buf[i+1], i++;
buf[j] = c;
if ( buf[j] != ' ' && buf[j] != '\n' && buf[j] != '\r' && buf[j] != '\t' )
j++;
}
buf[j] = 0;
return(j);
}
int _encode_json(unsigned char *dest,unsigned long *lenp,char *jsontext,unsigned long *sublenp)
{
int i,j,k,flag,retval,level = 9;
unsigned long len,sublen;
unsigned char *src,*substr;
len = strlen(jsontext);
src = (unsigned char *)clonestr(jsontext);
substr = malloc(len+1);
len = stripstr((char *)src,len);
for (i=k=0; src[i]!=0; i++)
{
if ( src[i] == '"' )
{
for (j=flag=0; j<Num_JSONwords&&j<128; j++)
if ( strncmp((char *)src+i+1,JSONlist[j].word,JSONlist[j].len) == 0 && src[i+1+JSONlist[j].len] == '"' && src[i+2+JSONlist[j].len] == ':' )
{
i += JSONlist[j].len + 2;
substr[k++] = 0x80 | j;
flag = 1;
break;
}
if ( flag != 0 )
continue;
}
else if ( (src[i] & 0x80) != 0 )
printf("unexpected control char in srctext\n");
substr[k++] = src[i];
}
substr[k] = 0;
*sublenp = sublen = strlen((char *)substr);
retval = compress2(dest,lenp,substr,sublen,level);
free(src); free(substr);
return(retval);
}
int _decode_json(unsigned char *decoded,long sublen,unsigned char *encoded,unsigned long *lenp)
{
int retval,i,j,k,wordi;
unsigned char *rawdecoded;
rawdecoded = malloc(sublen+1);
decoded[0] = 0;
retval = uncompress(rawdecoded,lenp,encoded,sublen);
if ( retval == 0 )
{
for (i=j=0; i<sublen; i++)
{
if ( (rawdecoded[i] & 0x80) != 0 )
{
wordi = (rawdecoded[i] & 0x7f);
decoded[j++] = '"';
for (k=0; k<JSONlist[wordi].len; k++)
decoded[j++] = JSONlist[wordi].word[k];
decoded[j++] = '"';
decoded[j++] = ':';
}
else decoded[j++] = rawdecoded[i];
}
decoded[j++] = 0;
}
free(rawdecoded);
return(retval);
}
int compare_jsontext(char *jsonA,char *jsonB)
{
int retval;
long lenA,lenB;
char *strA,*strB;
strA = clonestr(jsonA); strB = clonestr(jsonB);
lenA = stripstr(strA,strlen(strA));
lenB = stripstr(strB,strlen(strB));
if ( lenA == lenB )
retval = strcmp(strA,strB);
else retval = (int)(lenA - lenB);
free(strA); free(strB);
return(retval);
}
struct compressed_json *encode_json(char *jsontext)
{
int retval;
struct compressed_json *jsn = 0;
unsigned long len,sublen,origlen;
unsigned char *encoded;
origlen = len = strlen(jsontext);
encoded = malloc(len+1);
retval = _encode_json(encoded,&len,jsontext,&sublen);
if ( retval == 0 )
{
jsn = malloc(sizeof(*jsn) + len);
jsn->origlen = (uint32_t)origlen;
jsn->complen = (uint32_t)len;
jsn->sublen = (uint32_t)sublen;
memcpy(jsn->encoded,encoded,len);
} else printf("encode_json: error calling zlib.(%s)\n",jsontext);
free(encoded);
return(jsn);
}
char *decode_json(struct compressed_json *jsn)
{
int decoderet;
unsigned char *decoded;
unsigned long sublen;
sublen = jsn->sublen;
decoded = malloc(jsn->origlen+1);
//encodelen = jsn->complen;
decoderet = _decode_json(decoded,sublen,jsn->encoded,&sublen);
if ( decoderet == 0 )
return((char *)decoded);
free(decoded);
return(0);
}
int init_jsoncodec(char *jsontext)
{
FILE *fp;
int i,n;
struct compressed_json *jsn = 0;
char line[512],*word,*decoded;
unsigned long len,origlen;//,encodelen,sublen;
int cmpret = 0;
if ( Num_JSONwords == 0 && (fp= fopen("/tmp/words","r")) != 0 ) // grep all NXT .java files for response.put and req.getParameter > /tmp/words
{
n = 0;
while ( fgets(line,sizeof(line),fp) > 0 )
{
word = 0;
for (i=0; line[i]!=0; i++)
if ( line[i] == '"' )
{
word = line + i + 1;
break;
}
if ( word != 0 )
{
for (i++; line[i]!='"'&&line[i]!=0; i++)
;
line[i] = 0;
for (i=0; i<n; i++)
if ( strcmp(word,JSONlist[i].word) == 0 )
{
JSONlist[i].count++;
break;
}
if ( i == n )
{
n++;
JSONlist = realloc(JSONlist,n * sizeof(*JSONlist) * n);
JSONlist[i].word = clonestr(word);
JSONlist[i].len = (int)strlen(word);
JSONlist[i].count = 1;
}
}
}
printf("struct jsonwords JSONlist[] = { ");
for (i=0; i<n; i++)
printf("{\"%s\", %d, %d}, ",JSONlist[i].word,JSONlist[i].len,JSONlist[i].count);
printf("};\nint Num_JSONwords = %d;\n",n);
Num_JSONwords = n;
fclose(fp);
} else JSONlist = _JSONlist;
if ( jsontext != 0 )
{
len = origlen = strlen(jsontext);
jsn = encode_json(jsontext);
if ( jsn != 0 )
{
decoded = decode_json(jsn);
if ( decoded != 0 )
{
cmpret = compare_jsontext(jsontext,decoded);
printf("(%s).%ld ->\n(%s).%d retvals %d | compression ratio %.3f (orig.%d substition.%d compressed.%d)\n",jsontext,origlen,decoded,jsn->complen,cmpret,(double)origlen/jsn->complen,jsn->origlen,jsn->sublen,jsn->complen);
free(decoded);
}
free(jsn);
}
}
return(cmpret);
}
#endif
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