server: adjust the result of curl *

[xiekeyi98]

Now the result of curl will be displayed in oneline.
It is hard to read and hard to grep.
We should better make it pretty.

What problem does this PR solve?

Make http response more readable.

What is changed and how it works?

Change the interface of writeData

Side effects

All functions which use writeData to write Http Response WILL BE AFFECTED!!!!

Before

Keyi Xie [5:23 PM]
xiekeyi@ubuntu:~$ curl http://127.0.0.1:10080/settings
{"host":"0.0.0.0","advertise-address":"","port":4000,"cors":"","store":"mocktikv","path":"/tmp/tidb","socket":"","lease":"45s","run-ddl":true,"split-table":true,"token-limit":1000,"oom-action":"log","mem-quota-query":34359738368,"enable-streaming":false,"txn-local-latches":{"enabled":true,"capacity":2048000},"lower-case-table-names":2,"log":{"level":"info","format":"text","disable-timestamp":false,"file":{"filename":"","log-rotate":true,"max-size":300,"max-days":0,"max-backups":0},"slow-query-file":"","slow-threshold":300,"expensive-threshold":10000,"query-log-max-len":2048},"security":{"skip-grant-table":false,"ssl-ca":"","ssl-cert":"","ssl-key":"","cluster-ssl-ca":"","cluster-ssl-cert":"","cluster-ssl-key":""},"status":{"report-status":true,"status-port":10080,"metrics-addr":"","metrics-interval":15},"performance":{"max-procs":0,"max-memory":0,"tcp-keep-alive":true,"cross-join":true,"stats-lease":"3s","run-auto-analyze":true,"stmt-count-limit":5000,"feedback-probability":0.05,"query-feedback-limit":1024,"pseudo-estimate-ratio":0.8,"force-priority":"NO_PRIORITY"},"prepared-plan-cache":{"enabled":false,"capacity":100,"memory-guard-ratio":0.1},"opentracing":{"enable":false,"sampler":{"type":"const","param":1,"sampling-server-url":"","max-operations":0,"sampling-refresh-interval":0},"reporter":{"queue-size":0,"buffer-flush-interval":0,"log-spans":false,"local-agent-host-port":""},"rpc-metrics":false},"proxy-protocol":{"networks":"","header-timeout":5},"tikv-client":{"grpc-connection-count":16,"grpc-keepalive-time":10,"grpc-keepalive-timeout":3,"commit-timeout":"41s","max-txn-time-use":590,"max-batch-size":128,"overload-threshold":200,"max-batch-wait-time":0,"batch-wait-size":8},"binlog":{"enable":false,"write-timeout":"15s","ignore-error":false,"binlog-socket":""},"compatible-kill-query":false,"plugin":{"dir":"","load":""}}xiekeyi@ubuntu:~$

After

xiekeyi@ubuntu:~$ curl http://127.0.0.1:10080/settings
{
 "host": "0.0.0.0",
 "advertise-address": "",
 "port": 4000,
 "cors": "",
 "store": "mocktikv",
 "path": "/tmp/tidb",
 "socket": "",
 "lease": "45s",
 "run-ddl": true,
 "split-table": true,
 "token-limit": 1000,
 "oom-action": "log",
 "mem-quota-query": 34359738368,
 "enable-streaming": false,
 "txn-local-latches": {
  "enabled": true,
  "capacity": 2048000
 },
 "lower-case-table-names": 2,
 "log": {
  "level": "info",
  "format": "text",
  "disable-timestamp": false,
  "file": {
   "filename": "",
   "log-rotate": true,
   "max-size": 300,
   "max-days": 0,
   "max-backups": 0
  },
  "slow-query-file": "",
  "slow-threshold": 300,
  "expensive-threshold": 10000,
  "query-log-max-len": 2048
 },
 "security": {
  "skip-grant-table": false,
  "ssl-ca": "",
  "ssl-cert": "",
  "ssl-key": "",
  "cluster-ssl-ca": "",
  "cluster-ssl-cert": "",
  "cluster-ssl-key": ""
 },
 "status": {
  "report-status": true,
  "status-port": 10080,
  "metrics-addr": "",
  "metrics-interval": 15
 },
 "performance": {
  "max-procs": 0,
  "max-memory": 0,
  "tcp-keep-alive": true,
  "cross-join": true,
  "stats-lease": "3s",
  "run-auto-analyze": true,
  "stmt-count-limit": 5000,
  "feedback-probability": 0.05,
  "query-feedback-limit": 1024,
  "pseudo-estimate-ratio": 0.8,
  "force-priority": "NO_PRIORITY"
 },
 "prepared-plan-cache": {
  "enabled": false,
  "capacity": 100,
  "memory-guard-ratio": 0.1
 },
 "opentracing": {
  "enable": false,
  "sampler": {
   "type": "const",
   "param": 1,
   "sampling-server-url": "",
   "max-operations": 0,
   "sampling-refresh-interval": 0
  },
  "reporter": {
   "queue-size": 0,
   "buffer-flush-interval": 0,
   "log-spans": false,
   "local-agent-host-port": ""
  },
  "rpc-metrics": false
 },
 "proxy-protocol": {
  "networks": "",
  "header-timeout": 5
 },
 "tikv-client": {
  "grpc-connection-count": 16,
  "grpc-keepalive-time": 10,
  "grpc-keepalive-timeout": 3,
  "commit-timeout": "41s",
  "max-txn-time-use": 590,
  "max-batch-size": 128,
  "overload-threshold": 200,
  "max-batch-wait-time": 0,
  "batch-wait-size": 8
 },
 "binlog": {
  "enable": false,
  "write-timeout": "15s",
  "ignore-error": false,
  "binlog-socket": ""
 },
 "compatible-kill-query": false,
 "plugin": {
  "dir": "",
  "load": ""
 }
}xiekeyi@ubuntu:~$ 

[ngaut]

/run-all-tests

[codecov-io]

Codecov Report

Merging #9104 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #9104      +/-   ##
==========================================
+ Coverage   67.14%   67.14%   +<.01%     
==========================================
  Files         372      372              
  Lines       76974    76974              
==========================================
+ Hits        51684    51688       +4     
+ Misses      20660    20656       -4     
  Partials     4630     4630

Impacted Files	Coverage Δ
server/http_handler.go	36.94% <100%> (ø)	⬆️
store/tikv/lock_resolver.go	41.7% <0%> (-0.95%)	⬇️
expression/schema.go	94.11% <0%> (-0.85%)	⬇️
executor/distsql.go	73% <0%> (+0.46%)	⬆️
executor/join.go	78.38% <0%> (+0.52%)	⬆️
ddl/delete_range.go	79.36% <0%> (+1.58%)	⬆️

---

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[winkyao]

/run-unit-test

[imtbkcat]

LGTM

[winkyao]

LGTM