正则表达式基础知识请参阅《正则表达式基础知识》，本文使用正则表达式来匹配多行日志并从中解析出相应的信息。
假设现在有这样的SQL日志：
SELECT * FROM open_app WHERE 1 and `client_id` = 'a08f5e32909cc9418f' and `is_valid` = '1' order by id desc limit 32700,100;
# Time: 160616 10:05:10
# User@Host: shuqin[qqqq] @ [1.1.1.1] Id: 46765069
# Schema: db_xxx Last_errno: 0 Killed: 0
# Query_time: 0.561383 Lock_time: 0.000048 Rows_sent: 100 Rows_examined: 191166 Rows_affected: 0
# Bytes_sent: 14653
SET timestamp=1466042710;
SELECT * FROM open_app WHERE 1 and `client_id` = 'a08f5e32909cc9418f' and `is_valid` = '1' order by id desc limit 36700,100;
# User@Host: shuqin[ssss] @ [2.2.2.2] Id: 46765069
# Schema: db_yyy Last_errno: 0 Killed: 0
# Query_time: 0.501094 Lock_time: 0.000042 Rows_sent: 100 Rows_examined: 192966 Rows_affected: 0
# Bytes_sent: 14966
SET timestamp=1466042727;
要求从中解析出相应的信息， 有如下知识点：
(1) 默认正则是单行模式， 要匹配多行，需要开启 "多行模式"： MULTILINE； 对于点号，默认不匹配换行符，为了匹配换行符，也需要开启 "DOTALL模式"；
(2) 为了匹配每个多行日志，必须使用非贪婪模式，即在 .* 后面加 ? , 否则第一个匹配会匹配到末尾；
(3) 分而治之。编写正确的正则表达式匹配指定长字符串是不容易的，采用的策略是分而治之，将整个字符串分解成多个子串，分别匹配字串。这里每个字串都是一行，匹配好一行后，可以进一步在行内更细化的匹配；
(4) 无处不在的空格符要使用 \s* 或 \s+ 来增强健壮性； 固定的普通字符串可以在正则表达式中更好地标识各个字串，更容易地匹配到。
(5) Python 正则有两个常用用法： re.findall , re.match ; 前者的匹配结果是一个列表， 每个列表元素是一个元组， 匹配一个多行日志；元组的每个元素用来提取对应捕获分组的字符串； re.match 的匹配结果是一个 Match 对象， 可以通过 group(n) 来获取每个捕获分组的匹配字符串。下面的程序特意两种都用到了。对于多行匹配，使用了 re.findall ; 对于行内匹配，使用了 re.match ; 初学者常问这两者那两者有什么区别， 其实动手试试就知道了。
(6) 展示结构使用 Map. 解析出结果后，必然要展示或做成报告，使用 Map & List 结合的复合结构通常是非常适宜的选择。 比如这一例，如果要展示所有 SQL 日志详情，可以做成
{"tablename1": [{sqlobj11}, {sqlobj12}], ..., "tablenameN": [{sqlobjN1}, {sqlobjN2}] } ，每个 sqlobj 结构为：
{"sql": "select xxx", "QueryTime": 0.5600, ...}
要展示简要的报告，比如每个表的 SQL 统计， 可以做成
{"tablename1": {"sql11": 98, "sql12": 16}, ..., "tablenameN": {"sqlN1": 75, "sqlN2": 23} }
Python 程序实现：
import re globalRegex = r'^\s*(.*?)# (User@Host:.*?)# (Schema:.*?)# (Query_time:.*?)# Bytes_sent:(.*?)SET timestamp=(\d+);\s*$'
costRegex = r'Query_time:\s*(.*)\s*Lock_time:\s*(.*)\s*Rows_sent:\s*(\d+)\s*Rows_examined:\s*(\d+)\s*Rows_affected:\s*(\d+)\s*'
schemaRegex = r'Schema:\s*(.*)\s*Last_errno:(.*)\s*Killed:\s*(.*)\s*' def readSlowSqlFile(slowSqlFilename):
f = open(slowSqlFilename)
ftext = ''
for line in f:
ftext += line
f.close()
return ftext def findInText(regex, text):
return re.findall(regex, text, flags=re.DOTALL+re.MULTILINE) def parseSql(sqlobj, sqlText):
try:
if sqlText.find('#') != -1:
sqlobj['sql'] = sqlText.split('#')[0].strip()
sqlobj['time'] = sqlText.split('#')[1].strip()
else:
sqlobj['sql'] = sqlText.strip()
sqlobj['time'] = ''
except:
sqlobj['sql'] = sqlText.strip() def parseCost(sqlobj, costText):
matched = re.match(costRegex, costText)
sqlobj['Cost'] = costText
if matched:
sqlobj['QueryTime'] = matched.group(1).strip()
sqlobj['LockTime'] = matched.group(2).strip()
sqlobj['RowsSent'] = int(matched.group(3))
sqlobj['RowsExamined'] = int(matched.group(4))
sqlobj['RowsAffected'] = int(matched.group(5)) def parseSchema(sqlobj, schemaText):
matched = re.match(schemaRegex, schemaText)
sqlobj['Schema'] = schemaText
if matched:
sqlobj['Schema'] = matched.group(1).strip()
sqlobj['LastErrno'] = int(matched.group(2))
sqlobj['Killed'] = int(matched.group(3)) def parseSQLObj(matched):
sqlobj = {}
try:
if matched and len(matched) > 0:
parseSql(sqlobj, matched[0].strip())
sqlobj['UserHost'] = matched[1].strip()
sqlobj['ByteSent'] = int(matched[4])
sqlobj['timestamp'] = int(matched[5])
parseCost(sqlobj, matched[3].strip())
parseSchema(sqlobj, matched[2].strip())
return sqlobj
except:
return sqlobj if __name__ == '__main__': files = ['slow_sqls.txt'] alltext = ''
for f in files:
text = readSlowSqlFile(f)
alltext += text
allmatched = findInText(globalRegex, alltext) tablenames = ['open_app'] if not allmatched or len(allmatched) == 0:
print 'No matched. exit.'
exit(1) sqlobjMap = {}
for matched in allmatched:
sqlobj = parseSQLObj(matched)
if len(sqlobj) == 0:
continue
for tablename in tablenames:
if sqlobj['sql'].find(tablename) != -1:
if not sqlobjMap.get(tablename):
sqlobjMap[tablename] = []
sqlobjMap[tablename].append(sqlobj)
break resultMap = {}
for (tablename, sqlobjlist) in sqlobjMap.iteritems():
sqlstat = {}
for sqlobj in sqlobjlist:
if sqlobj['sql'] not in sqlstat:
sqlstat[sqlobj['sql']] = 0
sqlstat[sqlobj['sql']] += 1
resultMap[tablename] = sqlstat f_res = open('/tmp/res.txt', 'w')
f_res.write('-------------------------------------: \n')
f_res.write('Bref results: \n')
for (tablename, sqlstat) in resultMap.iteritems():
f_res.write('tablename: ' + tablename + '\n')
sortedsqlstat = sorted(sqlstat.iteritems(), key=lambda d:d[1], reverse = True)
for sortedsql in sortedsqlstat:
f_res.write('sql = %s\ncounts: %d\n\n' % (sortedsql[0], sortedsql[1]))
f_res.write('-------------------------------------: \n\n') f_res.write('-------------------------------------: \n')
f_res.write('Detail results: \n')
for (tablename, sqlobjlist) in sqlobjMap.iteritems():
f_res.write('tablename: ' + tablename + '\n')
f_res.write('sqlinfo: \n')
for sqlobj in sqlobjlist:
f_res.write('sql: ' + sqlobj['sql'] + ' QueryTime: ' + str(sqlobj.get('QueryTime')) + ' LockTime: ' + str(sqlobj.get('LockTime')) + '\n')
f_res.write(str(sqlobj) + '\n\n')
f_res.write('-------------------------------------: \n')
f_res.close()
可配置
事实上，可以做成可配置的。只要给定行间及行内关键字集合，可以分割多行及行内字段，就可以分别提取相应的内容。
这里有个基本函数 matchOneLine： 根据一个依序分割一行内容的关键字列表，匹配一行内容，得到每个关键字对应的内容。这个函数用于匹配行内内容。
配置方式： 采用列表的列表。列表中的每个元素列表是可以分割和匹配单行内容的关键字列表。 每个关键字都用于分割单行的某个区域的内容。 为了提升解析性能，这里对关键字列表进行了预编译正则表达式，以便在解析字符串的时候不做重复工作。
见如下代码：
#!/usr/bin/python
#_*_encoding:utf-8_*_ import re # config line keywords to seperate lines.
ksconf = [['S'], ['# User@Host:','Id:'] , ['# Schema:', 'Last_errno:', 'Killed:'], ['# Query_time:','Lock_time:', 'Rows_sent:', 'Rows_examined:', 'Rows_affected:'], ['# Bytes_sent:'], ['SET timestamp=']]
files = ['slow_sqls.txt'] #ksconf = [['id:'], ['name:'], ['able:']]
#files = ['stu.txt'] globalConf = {'ksconf': ksconf, 'files': files} def produceRegex(keywordlistInOneLine):
''' build the regex to match keywords in the list of keywordlistInOneLine '''
oneLineRegex = "^\s*"
oneLineRegex += "(.*?)".join(keywordlistInOneLine)
oneLineRegex += "(.*?)\s*$"
return oneLineRegex def readFile(filename):
f = open(filename)
ftext = ''
for line in f:
ftext += line
f.close()
return ftext def readAllFiles(files):
return ''.join(map(readFile, files)) def findInText(regex, text, linesConf):
'''
return a list of maps, each map is a match to multilines,
in a map, key is the line keyword
and value is the content corresponding to the key
'''
matched = regex.findall(text)
if empty(matched):
return [] allMatched = []
linePatternMap = buildLinePatternMap(linesConf)
for onematch in matched:
oneMatchedMap = buildOneMatchMap(linesConf, onematch, linePatternMap)
allMatched.append(oneMatchedMap)
return allMatched def buildOneMatchMap(linesConf, onematch, linePatternMap):
sepLines = map(lambda ks:ks[0], linesConf)
lenOflinesInOneMatch = len(sepLines)
lineMatchedMap = {}
for i in range(lenOflinesInOneMatch):
lineContent = sepLines[i] + onematch[i].strip()
linekey = getLineKey(linesConf[i])
lineMatchedMap.update(matchOneLine(linesConf[i], lineContent, linePatternMap)) return lineMatchedMap def matchOneLine(keywordlistOneLine, lineContent, patternMap):
'''
match lineContent with a list of keywords , and return a map
in which key is the keyword and value is the content matched the key.
eg.
keywordlistOneLine = ["host:", "ip:"] , lineContent = "host: qinhost ip: 1.1.1.1"
return {"host:": "qinhost", "ip": "1.1.1.1"}
''' ksmatchedResult = {}
if len(keywordlistOneLine) == 0 or lineContent.strip() == "":
return {}
linekey = getLineKey(keywordlistOneLine) if empty(patternMap):
linePattern = getLinePattern(keywordlistOneLine)
else:
linePattern = patternMap.get(linekey) lineMatched = linePattern.findall(lineContent)
if empty(lineMatched):
return {}
kslen = len(keywordlistOneLine)
if kslen == 1:
ksmatchedResult[cleankey(keywordlistOneLine[0])] = lineMatched[0].strip()
else:
for i in range(kslen):
ksmatchedResult[cleankey(keywordlistOneLine[i])] = lineMatched[0][i].strip() return ksmatchedResult def empty(obj):
return obj is None or len(obj) == 0 def cleankey(dirtykey):
''' clean unused characters in key '''
return re.sub(r"[# :]", "", dirtykey) def printMatched(allMatched, linesConf):
allks = []
for kslist in linesConf:
allks.extend(kslist)
for matched in allMatched:
for k in allks:
print cleankey(k) , "=>", matched.get(cleankey(k))
print '\n' def buildLinePatternMap(linesConf):
linePatternMap = {}
for keywordlistOneLine in linesConf:
linekey = getLineKey(keywordlistOneLine)
linePatternMap[linekey] = getLinePattern(keywordlistOneLine)
return linePatternMap def getLineKey(keywordlistForOneLine):
return "_".join(keywordlistForOneLine) def getLinePattern(keywordlistForOneLine):
return re.compile(produceRegex(keywordlistForOneLine)) def testMatchOneLine():
assert len(matchOneLine([], "haha", {})) == 0
assert len(matchOneLine(["host"], "", {})) == 0
assert len(matchOneLine("", "haha", {})) == 0
assert len(matchOneLine(["host", "ip"], "host:qqq addr: 1.1.1.1", {})) == 0 lineMatchMap1 = matchOneLine(["id:"], "id: 123456", {"id:": re.compile(produceRegex(["id:"]))})
assert lineMatchMap1.get("id") == "" lineMatchMap2 = matchOneLine(["host:", "ip:"], "host: qinhost ip: 1.1.1.1 ", {"host:_ip:": re.compile(produceRegex(["host:", "ip:"]))})
assert lineMatchMap2.get("host") == "qinhost"
assert lineMatchMap2.get("ip") == "1.1.1.1"
print 'testMatchOneLine passed.' if __name__ == '__main__': testMatchOneLine() files = globalConf['files']
linesConf = globalConf['ksconf']
sepLines = map(lambda ks:ks[0], linesConf) text = readAllFiles(files)
wholeRegex = produceRegex(sepLines)
print 'wholeRegex: ', wholeRegex compiledPattern = re.compile(wholeRegex, flags=re.DOTALL+re.MULTILINE)
allMatched = findInText(compiledPattern, text, linesConf)
printMatched(allMatched, linesConf)
如果想以下多行解析文本文件，只需要修改下 ksconf = [['id:'], ['name:'], ['able:']]。
id:1
name:shu
able:swim,study id:2
name:qin
able:sleep,run