software.amazon.disco.agent.sql

Class JdbcExecuteInterceptor

java.lang.Object

software.amazon.disco.agent.sql.JdbcExecuteInterceptor

All Implemented Interfaces:

software.amazon.disco.agent.interception.Installable

public class JdbcExecuteInterceptor
extends java.lang.Object
implements software.amazon.disco.agent.interception.Installable

This class represents the Disco interception of SQL queries performed using the JDBC. Some relevant information to know about the JDBC is that there are 3 Statement interfaces, which are implemented by various SQL databases such as MySQL. Statement classes are used to define queries then execute them. The inheritance of the Statement interfaces is: CallableStatement extends PreparedStatement extends Statement Callable and Prepared statements are typically used for queries whose query strings are defined in advanced and reused several times, whereas the base Statement class is more often used for one-off queries. Each statement interface defines three methods to execute queries, which are explained more below.

Field Summary

Fields

Modifier and Type	Field and Description
static software.amazon.disco.agent.logging.Logger	log
static java.lang.String	SQL_ORIGIN

Constructor Summary

Constructors

Constructor and Description
JdbcExecuteInterceptor()

Method Summary

Modifier and Type	Method and Description
static software.amazon.disco.agent.event.ServiceRequestEvent	enter(java.lang.String queryString, java.lang.String origin, java.sql.Statement stmt) This method is inlined at the beginning of all execute methods matched by buildMethodMatcher().
static void	exit(software.amazon.disco.agent.event.ServiceRequestEvent requestEvent, java.lang.Object response, java.lang.Throwable thrown) This method is inlined with an execute method at the moment it would return or throw a Throwable.
net.bytebuddy.agent.builder.AgentBuilder	install(net.bytebuddy.agent.builder.AgentBuilder agentBuilder) Installs the Disco SQL interception library into a Java program.
static java.lang.String	parseQueryFromStatement(java.lang.Class<?> preparedStatementClass, java.lang.Class<?> statementClass, java.sql.Statement stmt, java.lang.String queryString) This helper method attempts to get the query string in two ways before giving up and returning null.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface software.amazon.disco.agent.interception.Installable

handleArguments

Field Detail

log

public static final software.amazon.disco.agent.logging.Logger log

SQL_ORIGIN

public static final java.lang.String SQL_ORIGIN

See Also:

Constant Field Values

Constructor Detail

JdbcExecuteInterceptor

public JdbcExecuteInterceptor()

Method Detail

enter

@Advice.OnMethodEnter
public static software.amazon.disco.agent.event.ServiceRequestEvent enter(@Advice.Argument(value=0,optional=true)
                                                                                                java.lang.String queryString,
                                                                                                @Advice.Origin
                                                                                                java.lang.String origin,
                                                                                                @Advice.This
                                                                                                java.sql.Statement stmt)

This method is inlined at the beginning of all execute methods matched by buildMethodMatcher(). It extracts some information from the intercepted execute method and calling object, then publishes a SQL query request event as a ServiceDownstreamRequestEvent. The Query "service" is modeled as: Origin = "SQL" Service = Target database name Operation = SQL query string Request = JDBC Statement object constructed by user, intercepted by ByteBuddy Must be public for use in Advice methods https://github.com/raphw/byte-buddy/issues/761

Parameters:

queryString - the first parameter of the method, in the case where it is the queryString

origin - Identifier of the intercepted method, for debugging/logging

stmt - concrete statement class being used to make the query

Returns:

a ServiceDownstreamRequestEvent with fields populated on a best effort basis

exit

@Advice.OnMethodExit(onThrowable=java.lang.Throwable.class)
public static void exit(@Advice.Enter
                                                                                    software.amazon.disco.agent.event.ServiceRequestEvent requestEvent,
                                                                                    @Advice.Return
                                                                                    java.lang.Object response,
                                                                                    @Advice.Thrown
                                                                                    java.lang.Throwable thrown)

This method is inlined with an execute method at the moment it would return or throw a Throwable. It extracts the response and throwable if any and publishes a ServiceDownstreamResponseEvent. See enter(java.lang.String, java.lang.String, java.sql.Statement) for Event model. Must be public for use in Advice methods https://github.com/raphw/byte-buddy/issues/761

Parameters:

requestEvent - the returned value of enter(java.lang.String, java.lang.String, java.sql.Statement) method, passed in using the Enter annotation

response - the response of the JDBC execute method or null if an exception was thrown, passed in using the Return annotation

thrown - the Throwable thrown by the query, or null if query was successful. Passed in using the Thrown annotation. Typically a SQLException.

install

public net.bytebuddy.agent.builder.AgentBuilder install(net.bytebuddy.agent.builder.AgentBuilder agentBuilder)

Installs the Disco SQL interception library into a Java program. Intended to be invoked during an agent's premain.

Specified by:

install in interface software.amazon.disco.agent.interception.Installable

Parameters:

agentBuilder - - an AgentBuilder to append instructions to

Returns:

- the AgentBuilder object for chaining

parseQueryFromStatement

public static java.lang.String parseQueryFromStatement(java.lang.Class<?> preparedStatementClass,
                                                       java.lang.Class<?> statementClass,
                                                       java.sql.Statement stmt,
                                                       java.lang.String queryString)
                                                throws java.lang.NoSuchMethodException

This helper method attempts to get the query string in two ways before giving up and returning null. The first is just retrieving it from the arguments passed to the execute method being intercepted. If it is not present there, then we must be dealing with a Prepared or Callable statement that had its query string pre-loaded rather than passed as an argument. In this case, there is no way provided by the JDBC to extract the query. However many DB Drivers implement the toString method on their PreparedStatement class to return the pre-loaded SQL query string. So the second way is to check if the toString method is overridden, and if so we use it. See: https://stackoverflow.com/questions/2382532/how-can-i-get-the-sql-of-a-preparedstatement Must be public for use in Advice methods https://github.com/raphw/byte-buddy/issues/761

Parameters:

preparedStatementClass - must be literally 'PreparedStatement.class'. Necessary because this method is called from somewhere this class may not be available, so it must be passed in

statementClass - must be literally 'Statement.class'. Necessary for the same reason as preparedStatementClass

stmt - the JDBC Statement object being used to make the query

queryString - if the first param of the intercepted method was a queryString, this is not-null.

Returns:

the query string used in this SQL query if readable, or null otherwise

Throws:

java.lang.NoSuchMethodException