第2步：捉迷藏，kafka的main入口在哪里？

第2步：捉迷藏，kafka的main入口在哪里？

1、看一下启动kafka的脚本 nohup /usr/local/kafka_2.10-0.9.0.1/bin/kafka-server-start.sh  /usr/local/kafka_2.10-0.9.0.1/config/server.properties &

我们看一下bin目录下的kafka-server-start.sh脚本： if [ $# -lt 1 ]; //参数的个数小于1 then  echo "USAGE: $0 [-daemon] server.properties [--override property=value]*"  exit 1 fi base_dir=$(dirname $0)

if [ "x$KAFKA_LOG4J_OPTS" = "x" ]; then     export KAFKA_LOG4J_OPTS="-Dlog4j.configuration=file:$base_dir/../config/log4j.properties" fi

if [ "x$KAFKA_HEAP_OPTS" = "x" ]; then     export KAFKA_HEAP_OPTS="-Xmx1G -Xms1G" fi

EXTRA_ARGS="-name kafkaServer -loggc"

COMMAND=$1 case $COMMAND in   -daemon)     EXTRA_ARGS="-daemon "$EXTRA_ARGS     shift     ;;   *)     ;; esac

exec $base_dir/kafka-run-class.sh $EXTRA_ARGS kafka.Kafka "$@"

//要看一下kafka-run-class.sh  kafka.Kafka类

2、看一下kafka创建topic的脚本kafka-topics.sh

kafka-topics.sh --create --zookeeper master:2181,worker1:2181,worker2:2181 --replication-factor 1 --partitions 1 -- topic SparkStreamingDirected   kafka-topics.sh 只有一句话

exec $(dirname $0)/kafka-run-class.sh kafka.admin.TopicCommand "$@" linux说明： $0：Shell本身的文件名 $@：表示所有脚本参数的内容 $#:表示返回所有脚本参数的个数。

要看kafka-run-class.sh脚本 kafka.admin.TopicCommand

4、kafka-run-class.sh 探秘

 

if [ $# -lt 1 ]; then   echo "USAGE: $0 [-daemon] [-name servicename] [-loggc] classname [opts]"   exit 1 fi

base_dir=$(dirname $0)/..

if [ -z "$SCALA_VERSION" ]; then  SCALA_VERSION=2.10.5 fi

if [ -z "$SCALA_BINARY_VERSION" ]; then  SCALA_BINARY_VERSION=2.10 fi

# run ./gradlew copyDependantLibs to get all dependant jars in a local dir shopt -s nullglob for dir in $base_dir/core/build/dependant-libs-${SCALA_VERSION}*; do   CLASSPATH=$CLASSPATH:$dir/* done

for file in $base_dir/examples/build/libs//kafka-examples*.jar; do   CLASSPATH=$CLASSPATH:$file done

for file in $base_dir/clients/build/libs/kafka-clients*.jar; do   CLASSPATH=$CLASSPATH:$file done

for file in $base_dir/tools/build/libs/kafka-tools*.jar; do   CLASSPATH=$CLASSPATH:$file done

for dir in $base_dir/tools/build/dependant-libs-${SCALA_VERSION}*; do   CLASSPATH=$CLASSPATH:$dir/* done

for cc_pkg in "api" "runtime" "file" "json" do   for file in $base_dir/connect/${cc_pkg}/build/libs/connect-${cc_pkg}*.jar;   do     CLASSPATH=$CLASSPATH:$file   done   if [ -d "$base_dir/connect/${cc_pkg}/build/dependant-libs" ] ; then     CLASSPATH=$CLASSPATH:$base_dir/connect/${cc_pkg}/build/dependant-libs/*   fi done

# classpath addition for release CLASSPATH=$CLASSPATH:$base_dir/libs/*

for file in $base_dir/core/build/libs/kafka_${SCALA_BINARY_VERSION}*.jar; do   CLASSPATH=$CLASSPATH:$file done shopt -u nullglob

# JMX settings if [ -z "$KAFKA_JMX_OPTS" ]; then   KAFKA_JMX_OPTS="-Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.authenticate=false  -Dcom.sun.management.jmxremote.ssl=false " fi

# JMX port to use if [  $JMX_PORT ]; then   KAFKA_JMX_OPTS="$KAFKA_JMX_OPTS -Dcom.sun.management.jmxremote.port=$JMX_PORT " fi

# Log directory to use if [ "x$LOG_DIR" = "x" ]; then     LOG_DIR="$base_dir/logs" fi

# Log4j settings if [ -z "$KAFKA_LOG4J_OPTS" ]; then   # Log to console. This is a tool.   KAFKA_LOG4J_OPTS="-Dlog4j.configuration=file:$base_dir/config/tools-log4j.properties" else   # create logs directory   if [ ! -d "$LOG_DIR" ]; then     mkdir -p "$LOG_DIR"   fi fi

KAFKA_LOG4J_OPTS="-Dkafka.logs.dir=$LOG_DIR $KAFKA_LOG4J_OPTS"

# Generic jvm settings you want to add if [ -z "$KAFKA_OPTS" ]; then   KAFKA_OPTS="" fi

# Which java to use if [ -z "$JAVA_HOME" ]; then   JAVA="java" else   JAVA="$JAVA_HOME/bin/java" fi

# Memory options if [ -z "$KAFKA_HEAP_OPTS" ]; then   KAFKA_HEAP_OPTS="-Xmx256M" fi

# JVM performance options if [ -z "$KAFKA_JVM_PERFORMANCE_OPTS" ]; then   KAFKA_JVM_PERFORMANCE_OPTS="-server -XX:+UseG1GC -XX:MaxGCPauseMillis=20 -XX:InitiatingHeapOccupancyPercent=35 -XX:+DisableExplicitGC -Djava.awt.headless=true" fi

while [ $# -gt 0 ]; do   COMMAND=$1   case $COMMAND in     -name)       DAEMON_NAME=$2       CONSOLE_OUTPUT_FILE=$LOG_DIR/$DAEMON_NAME.out       shift 2       ;;     -loggc)       if [ -z "$KAFKA_GC_LOG_OPTS" ]; then         GC_LOG_ENABLED="true"       fi       shift       ;;     -daemon)       DAEMON_MODE="true"       shift       ;;     *)       break       ;;   esac done

# GC options GC_FILE_SUFFIX='-gc.log' GC_LOG_FILE_NAME='' if [ "x$GC_LOG_ENABLED" = "xtrue" ]; then   GC_LOG_FILE_NAME=$DAEMON_NAME$GC_FILE_SUFFIX   KAFKA_GC_LOG_OPTS="-Xloggc:$LOG_DIR/$GC_LOG_FILE_NAME -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCTimeStamps " fi

# Launch mode if [ "x$DAEMON_MODE" = "xtrue" ]; then   nohup $JAVA $KAFKA_HEAP_OPTS $KAFKA_JVM_PERFORMANCE_OPTS $KAFKA_GC_LOG_OPTS $KAFKA_JMX_OPTS $KAFKA_LOG4J_OPTS -cp $CLASSPATH $KAFKA_OPTS "$@" > "$CONSOLE_OUTPUT_FILE" 2>&1 < /dev/null & else   exec $JAVA $KAFKA_HEAP_OPTS $KAFKA_JVM_PERFORMANCE_OPTS $KAFKA_GC_LOG_OPTS $KAFKA_JMX_OPTS $KAFKA_LOG4J_OPTS -cp $CLASSPATH $KAFKA_OPTS "$@" fi

前面一大堆参数略过了，最后的一行启动模式 Launch mode。

exec $JAVA $KAFKA_HEAP_OPTS $KAFKA_JVM_PERFORMANCE_OPTS $KAFKA_GC_LOG_OPTS $KAFKA_JMX_OPTS $KAFKA_LOG4J_OPTS -cp $CLASSPATH $KAFKA_OPTS "$@"

5、启动后就到了kafka的类入口了。

启动kafka的main入口：kafka.kafka

kafka建立topic的入口：kafka.admin.TopicCommand