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Commit 933072bd authored by JW Wang's avatar JW Wang Committed by Android (Google) Code Review
Browse files

Merge changes from topic "bug162286562" 

* changes:
  Fix #removeChildSessionId (4/n)
  Fix #removeChildSessionId (3/n)
  Fix #addChildSessionId (2/n)
  Fix #addChildSessionId (1/n)
  Ensure mutation to multiple objects is done atomically
parents 96650db0 b1d2b9dc

services/core/java/com/android/server/pm/PackageInstallerSession.java

+70 −17
Original line number Diff line number Diff line
@@ -157,6 +157,7 @@ import java.util.Arrays; 
import java.util.List;

import java.util.Objects;

import java.util.Set;

import java.util.concurrent.atomic.AtomicBoolean;

import java.util.concurrent.atomic.AtomicInteger;



public class PackageInstallerSession extends IPackageInstallerSession.Stub {
@@ -262,6 +263,12 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub { 


    private final Object mLock = new Object();



    /**

     * Used to detect and reject concurrent access to this session object to ensure mutation

     * to multiple objects like {@link #addChildSessionId} are done atomically.

     */

    private final AtomicBoolean mTransactionLock = new AtomicBoolean(false);



    /** Timestamp of the last time this session changed state  */

    @GuardedBy("mLock")

    private long updatedMillis;
@@ -3162,12 +3169,39 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub { 
        }

    }



    private void acquireTransactionLock() {

        if (!mTransactionLock.compareAndSet(false, true)) {

            throw new UnsupportedOperationException("Concurrent access not supported");

        }

    }



    private void releaseTransactionLock() {

        mTransactionLock.compareAndSet(true, false);

    }



    @Override

    public void addChildSessionId(int childSessionId) {

        if (!params.isMultiPackage) {

            throw new IllegalStateException("Single-session " + sessionId + " can't have child.");

        }



        final PackageInstallerSession childSession = mSessionProvider.getSession(childSessionId);

        if (childSession == null || !childSession.canBeAddedAsChild(sessionId)) {

        if (childSession == null) {

            throw new IllegalStateException("Unable to add child session " + childSessionId

                    + " as it does not exist.");

        }

        if (childSession.params.isMultiPackage) {

            throw new IllegalStateException("Multi-session " + childSessionId

                    + " can't be a child.");

        }



        try {

            acquireTransactionLock();

            childSession.acquireTransactionLock();



            if (!childSession.canBeAddedAsChild(sessionId)) {

                throw new IllegalStateException("Unable to add child session " + childSessionId

                            + " as it does not exist or is in an invalid state.");

                        + " as it is in an invalid state.");

            }

            synchronized (mLock) {

                assertCallerIsOwnerOrRootLocked();
@@ -3180,22 +3214,41 @@ public class PackageInstallerSession extends IPackageInstallerSession.Stub { 
                childSession.setParentSessionId(this.sessionId);

                addChildSessionIdLocked(childSessionId);

            }

        } finally {

            releaseTransactionLock();

            childSession.releaseTransactionLock();

        }

    }



    @Override

    public void removeChildSessionId(int sessionId) {

        final PackageInstallerSession session = mSessionProvider.getSession(sessionId);

        synchronized (mLock) {

            final int indexOfSession = mChildSessionIds.indexOfKey(sessionId);

        try {

            acquireTransactionLock();

            if (session != null) {

                session.setParentSessionId(SessionInfo.INVALID_ID);

                session.acquireTransactionLock();

            }



            synchronized (mLock) {

                assertCallerIsOwnerOrRootLocked();

                assertPreparedAndNotSealedLocked("removeChildSessionId");



                final int indexOfSession = mChildSessionIds.indexOfKey(sessionId);

                if (indexOfSession < 0) {

                    // not added in the first place; no-op

                    return;

                }

                if (session != null) {

                    session.setParentSessionId(SessionInfo.INVALID_ID);

                }

                mChildSessionIds.removeAt(indexOfSession);

            }

        } finally {

            releaseTransactionLock();

            if (session != null) {

                session.releaseTransactionLock();

            }

        }

    }



    /**