com.android.tools.lint.checks.JavaPerformanceDetector Maven / Gradle / Ivy
/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.tools.lint.checks;
import static com.android.SdkConstants.SUPPORT_LIB_ARTIFACT;
import static com.android.tools.lint.client.api.JavaParser.TYPE_BOOLEAN;
import static com.android.tools.lint.client.api.JavaParser.TYPE_BOOLEAN_WRAPPER;
import static com.android.tools.lint.client.api.JavaParser.TYPE_BYTE_WRAPPER;
import static com.android.tools.lint.client.api.JavaParser.TYPE_CHARACTER_WRAPPER;
import static com.android.tools.lint.client.api.JavaParser.TYPE_DOUBLE_WRAPPER;
import static com.android.tools.lint.client.api.JavaParser.TYPE_FLOAT_WRAPPER;
import static com.android.tools.lint.client.api.JavaParser.TYPE_INT;
import static com.android.tools.lint.client.api.JavaParser.TYPE_INTEGER_WRAPPER;
import static com.android.tools.lint.client.api.JavaParser.TYPE_LONG_WRAPPER;
import static com.android.tools.lint.detector.api.LintUtils.skipParentheses;
import com.android.annotations.NonNull;
import com.android.annotations.Nullable;
import com.android.tools.lint.client.api.JavaEvaluator;
import com.android.tools.lint.detector.api.Category;
import com.android.tools.lint.detector.api.Detector;
import com.android.tools.lint.detector.api.Implementation;
import com.android.tools.lint.detector.api.Issue;
import com.android.tools.lint.detector.api.JavaContext;
import com.android.tools.lint.detector.api.Scope;
import com.android.tools.lint.detector.api.Severity;
import com.android.tools.lint.detector.api.TextFormat;
import com.google.common.collect.Sets;
import com.google.common.collect.Sets.SetView;
import com.intellij.psi.JavaElementVisitor;
import com.intellij.psi.JavaRecursiveElementVisitor;
import com.intellij.psi.PsiAssignmentExpression;
import com.intellij.psi.PsiBinaryExpression;
import com.intellij.psi.PsiElement;
import com.intellij.psi.PsiExpression;
import com.intellij.psi.PsiIdentifier;
import com.intellij.psi.PsiIfStatement;
import com.intellij.psi.PsiJavaCodeReferenceElement;
import com.intellij.psi.PsiMethod;
import com.intellij.psi.PsiMethodCallExpression;
import com.intellij.psi.PsiNewExpression;
import com.intellij.psi.PsiParenthesizedExpression;
import com.intellij.psi.PsiPrefixExpression;
import com.intellij.psi.PsiReferenceExpression;
import com.intellij.psi.PsiSuperExpression;
import com.intellij.psi.PsiThisExpression;
import com.intellij.psi.PsiThrowStatement;
import com.intellij.psi.PsiType;
import com.intellij.psi.util.PsiTreeUtil;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
/**
* Looks for performance issues in Java files, such as memory allocations during
* drawing operations and using HashMap instead of SparseArray.
*/
public class JavaPerformanceDetector extends Detector implements Detector.JavaPsiScanner {
private static final Implementation IMPLEMENTATION = new Implementation(
JavaPerformanceDetector.class,
Scope.JAVA_FILE_SCOPE);
/** Allocating objects during a paint method */
public static final Issue PAINT_ALLOC = Issue.create(
"DrawAllocation", //$NON-NLS-1$
"Memory allocations within drawing code",
"You should avoid allocating objects during a drawing or layout operation. These " +
"are called frequently, so a smooth UI can be interrupted by garbage collection " +
"pauses caused by the object allocations.\n" +
"\n" +
"The way this is generally handled is to allocate the needed objects up front " +
"and to reuse them for each drawing operation.\n" +
"\n" +
"Some methods allocate memory on your behalf (such as `Bitmap.create`), and these " +
"should be handled in the same way.",
Category.PERFORMANCE,
9,
Severity.WARNING,
IMPLEMENTATION);
/** Using HashMaps where SparseArray would be better */
public static final Issue USE_SPARSE_ARRAY = Issue.create(
"UseSparseArrays", //$NON-NLS-1$
"HashMap can be replaced with SparseArray",
"For maps where the keys are of type integer, it's typically more efficient to " +
"use the Android `SparseArray` API. This check identifies scenarios where you might " +
"want to consider using `SparseArray` instead of `HashMap` for better performance.\n" +
"\n" +
"This is *particularly* useful when the value types are primitives like ints, " +
"where you can use `SparseIntArray` and avoid auto-boxing the values from `int` to " +
"`Integer`.\n" +
"\n" +
"If you need to construct a `HashMap` because you need to call an API outside of " +
"your control which requires a `Map`, you can suppress this warning using for " +
"example the `@SuppressLint` annotation.",
Category.PERFORMANCE,
4,
Severity.WARNING,
IMPLEMENTATION);
/** Using {@code new Integer()} instead of the more efficient {@code Integer.valueOf} */
public static final Issue USE_VALUE_OF = Issue.create(
"UseValueOf", //$NON-NLS-1$
"Should use `valueOf` instead of `new`",
"You should not call the constructor for wrapper classes directly, such as" +
"`new Integer(42)`. Instead, call the `valueOf` factory method, such as " +
"`Integer.valueOf(42)`. This will typically use less memory because common integers " +
"such as 0 and 1 will share a single instance.",
Category.PERFORMANCE,
4,
Severity.WARNING,
IMPLEMENTATION);
static final String ON_MEASURE = "onMeasure";
static final String ON_DRAW = "onDraw";
static final String ON_LAYOUT = "onLayout";
private static final String LAYOUT = "layout";
private static final String HASH_MAP = "java.util.HashMap";
private static final String SPARSE_ARRAY = "android.util.SparseArray";
public static final String CLASS_CANVAS = "android.graphics.Canvas";
/** Constructs a new {@link JavaPerformanceDetector} check */
public JavaPerformanceDetector() {
}
// ---- Implements JavaScanner ----
@Override
public List> getApplicablePsiTypes() {
List> types = new ArrayList>(3);
types.add(PsiNewExpression.class);
types.add(PsiMethod.class);
types.add(PsiMethodCallExpression.class);
return types;
}
@Override
public JavaElementVisitor createPsiVisitor(@NonNull JavaContext context) {
return new PerformanceVisitor(context);
}
private static class PerformanceVisitor extends JavaElementVisitor {
private final JavaContext mContext;
private final boolean mCheckMaps;
private final boolean mCheckAllocations;
private final boolean mCheckValueOf;
/** Whether allocations should be "flagged" in the current method */
private boolean mFlagAllocations;
public PerformanceVisitor(JavaContext context) {
mContext = context;
mCheckAllocations = context.isEnabled(PAINT_ALLOC);
mCheckMaps = context.isEnabled(USE_SPARSE_ARRAY);
mCheckValueOf = context.isEnabled(USE_VALUE_OF);
}
@Override
public void visitMethod(PsiMethod node) {
mFlagAllocations = isBlockedAllocationMethod(node);
}
@Override
public void visitNewExpression(PsiNewExpression node) {
String typeName = null;
PsiJavaCodeReferenceElement classReference = node.getClassReference();
if (mCheckMaps || mCheckValueOf) {
if (classReference != null) {
typeName = classReference.getQualifiedName();
}
}
if (mCheckMaps) {
// TODO: Should we handle factory method constructions of HashMaps as well,
// e.g. via Guava? This is a bit trickier since we need to infer the type
// arguments from the calling context.
if (HASH_MAP.equals(typeName)) {
checkHashMap(node, classReference);
} else if (SPARSE_ARRAY.equals(typeName)) {
checkSparseArray(node, classReference);
}
}
if (mCheckValueOf) {
if (typeName != null
&& (typeName.equals(TYPE_INTEGER_WRAPPER)
|| typeName.equals(TYPE_BOOLEAN_WRAPPER)
|| typeName.equals(TYPE_FLOAT_WRAPPER)
|| typeName.equals(TYPE_CHARACTER_WRAPPER)
|| typeName.equals(TYPE_LONG_WRAPPER)
|| typeName.equals(TYPE_DOUBLE_WRAPPER)
|| typeName.equals(TYPE_BYTE_WRAPPER))
//&& node.astTypeReference().astParts().size() == 1
&& node.getArgumentList() != null
&& node.getArgumentList().getExpressions().length == 1) {
String argument = node.getArgumentList().getExpressions()[0].getText();
mContext.report(USE_VALUE_OF, node, mContext.getLocation(node), getUseValueOfErrorMessage(
typeName, argument));
}
}
if (mFlagAllocations
&& !(skipParentheses(node.getParent()) instanceof PsiThrowStatement)
&& mCheckAllocations) {
// Make sure we're still inside the method declaration that marked
// mInDraw as true, in case we've left it and we're in a static
// block or something:
PsiMethod method = PsiTreeUtil.getParentOfType(node, PsiMethod.class);
if (method != null && isBlockedAllocationMethod(method)
&& !isLazilyInitialized(node)) {
reportAllocation(node);
}
}
}
private void reportAllocation(PsiElement node) {
mContext.report(PAINT_ALLOC, node, mContext.getLocation(node),
"Avoid object allocations during draw/layout operations (preallocate and " +
"reuse instead)");
}
@Override
public void visitMethodCallExpression(PsiMethodCallExpression node) {
if (!mFlagAllocations) {
return;
}
PsiReferenceExpression expression = node.getMethodExpression();
PsiElement qualifier = expression.getQualifier();
if (qualifier == null) {
return;
}
String methodName = expression.getReferenceName();
if (methodName == null) {
return;
}
// Look for forbidden methods
if (methodName.equals("createBitmap") //$NON-NLS-1$
|| methodName.equals("createScaledBitmap")) { //$NON-NLS-1$
PsiMethod method = node.resolveMethod();
if (method != null && mContext.getEvaluator().isMemberInClass(method,
"android.graphics.Bitmap") && !isLazilyInitialized(node)) {
reportAllocation(node);
}
} else if (methodName.startsWith("decode")) { //$NON-NLS-1$
// decodeFile, decodeByteArray, ...
PsiMethod method = node.resolveMethod();
if (method != null && mContext.getEvaluator().isMemberInClass(method,
"android.graphics.BitmapFactory") && !isLazilyInitialized(node)) {
reportAllocation(node);
}
} else if (methodName.equals("getClipBounds")) { //$NON-NLS-1$
if (node.getArgumentList().getExpressions().length == 0) {
mContext.report(PAINT_ALLOC, node, mContext.getLocation(node),
"Avoid object allocations during draw operations: Use " +
"`Canvas.getClipBounds(Rect)` instead of `Canvas.getClipBounds()` " +
"which allocates a temporary `Rect`");
}
}
}
/**
* Check whether the given invocation is done as a lazy initialization,
* e.g. {@code if (foo == null) foo = new Foo();}.
*
* This tries to also handle the scenario where the check is on some
* other variable - e.g.
*
* if (foo == null) {
* foo == init1();
* bar = new Bar();
* }
*
* or
*
* if (!initialized) {
* initialized = true;
* bar = new Bar();
* }
*
*/
private static boolean isLazilyInitialized(PsiElement node) {
PsiElement curr = node.getParent();
while (curr != null) {
if (curr instanceof PsiMethod) {
return false;
} else if (curr instanceof PsiIfStatement) {
PsiIfStatement ifNode = (PsiIfStatement) curr;
// See if the if block represents a lazy initialization:
// compute all variable names seen in the condition
// (e.g. for "if (foo == null || bar != foo)" the result is "foo,bar"),
// and then compute all variables assigned to in the if body,
// and if there is an overlap, we'll consider the whole if block
// guarded (so lazily initialized and an allocation we won't complain
// about.)
List assignments = new ArrayList();
AssignmentTracker visitor = new AssignmentTracker(assignments);
if (ifNode.getThenBranch() != null) {
ifNode.getThenBranch().accept(visitor);
}
if (!assignments.isEmpty()) {
List references = new ArrayList();
addReferencedVariables(references, ifNode.getCondition());
if (!references.isEmpty()) {
SetView intersection = Sets.intersection(
new HashSet(assignments),
new HashSet(references));
return !intersection.isEmpty();
}
}
return false;
}
curr = curr.getParent();
}
return false;
}
/** Adds any variables referenced in the given expression into the given list */
private static void addReferencedVariables(
@NonNull Collection variables,
@Nullable PsiExpression expression) {
if (expression instanceof PsiBinaryExpression) {
PsiBinaryExpression binary = (PsiBinaryExpression) expression;
addReferencedVariables(variables, binary.getLOperand());
addReferencedVariables(variables, binary.getROperand());
} else if (expression instanceof PsiPrefixExpression) {
PsiPrefixExpression unary = (PsiPrefixExpression) expression;
addReferencedVariables(variables, unary.getOperand());
} else if (expression instanceof PsiParenthesizedExpression) {
PsiParenthesizedExpression exp = (PsiParenthesizedExpression) expression;
addReferencedVariables(variables, exp.getExpression());
} else if (expression instanceof PsiIdentifier) {
PsiIdentifier reference = (PsiIdentifier) expression;
variables.add(reference.getText());
} else if (expression instanceof PsiReferenceExpression) {
PsiReferenceExpression ref = (PsiReferenceExpression) expression;
PsiElement qualifier = ref.getQualifier();
if (qualifier != null) {
if (qualifier instanceof PsiThisExpression ||
qualifier instanceof PsiSuperExpression) {
variables.add(ref.getReferenceName());
}
} else {
variables.add(ref.getReferenceName());
}
}
}
/**
* Returns whether the given method declaration represents a method
* where allocating objects is not allowed for performance reasons
*/
private boolean isBlockedAllocationMethod(
@NonNull PsiMethod node) {
JavaEvaluator evaluator = mContext.getEvaluator();
return isOnDrawMethod(evaluator, node)
|| isOnMeasureMethod(evaluator, node)
|| isOnLayoutMethod(evaluator, node)
|| isLayoutMethod(evaluator, node);
}
/**
* Returns true if this method looks like it's overriding android.view.View's
* {@code protected void onDraw(Canvas canvas)}
*/
private static boolean isOnDrawMethod(
@NonNull JavaEvaluator evaluator,
@NonNull PsiMethod node) {
return ON_DRAW.equals(node.getName()) && evaluator.parametersMatch(node, CLASS_CANVAS);
}
/**
* Returns true if this method looks like it's overriding
* android.view.View's
* {@code protected void onLayout(boolean changed, int left, int top,
* int right, int bottom)}
*/
private static boolean isOnLayoutMethod(
@NonNull JavaEvaluator evaluator,
@NonNull PsiMethod node) {
return ON_LAYOUT.equals(node.getName()) && evaluator.parametersMatch(node,
TYPE_BOOLEAN, TYPE_INT, TYPE_INT, TYPE_INT, TYPE_INT);
}
/**
* Returns true if this method looks like it's overriding android.view.View's
* {@code protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)}
*/
private static boolean isOnMeasureMethod(
@NonNull JavaEvaluator evaluator,
@NonNull PsiMethod node) {
return ON_MEASURE.equals(node.getName()) && evaluator.parametersMatch(node,
TYPE_INT, TYPE_INT);
}
/**
* Returns true if this method looks like it's overriding android.view.View's
* {@code public void layout(int l, int t, int r, int b)}
*/
private static boolean isLayoutMethod(
@NonNull JavaEvaluator evaluator,
@NonNull PsiMethod node) {
return LAYOUT.equals(node.getName()) && evaluator.parametersMatch(node,
TYPE_INT, TYPE_INT, TYPE_INT, TYPE_INT);
}
/**
* Checks whether the given constructor call and type reference refers
* to a HashMap constructor call that is eligible for replacement by a
* SparseArray call instead
*/
private void checkHashMap(
@NonNull PsiNewExpression node,
@NonNull PsiJavaCodeReferenceElement reference) {
PsiType[] types = reference.getTypeParameters();
if (types.length == 2) {
PsiType first = types[0];
String typeName = first.getCanonicalText();
int minSdk = mContext.getMainProject().getMinSdk();
if (TYPE_INTEGER_WRAPPER.equals(typeName) || TYPE_BYTE_WRAPPER.equals(typeName)) {
String valueType = types[1].getCanonicalText();
if (valueType.equals(TYPE_INTEGER_WRAPPER)) {
mContext.report(USE_SPARSE_ARRAY, node, mContext.getLocation(node),
"Use new `SparseIntArray(...)` instead for better performance");
} else if (valueType.equals(TYPE_LONG_WRAPPER) && minSdk >= 18) {
mContext.report(USE_SPARSE_ARRAY, node, mContext.getLocation(node),
"Use `new SparseLongArray(...)` instead for better performance");
} else if (valueType.equals(TYPE_BOOLEAN_WRAPPER)) {
mContext.report(USE_SPARSE_ARRAY, node, mContext.getLocation(node),
"Use `new SparseBooleanArray(...)` instead for better performance");
} else {
mContext.report(USE_SPARSE_ARRAY, node, mContext.getLocation(node),
String.format(
"Use `new SparseArray<%1$s>(...)` instead for better performance",
valueType.substring(valueType.lastIndexOf('.') + 1)));
}
} else if (TYPE_LONG_WRAPPER.equals(typeName) && (minSdk >= 16 ||
Boolean.TRUE == mContext.getMainProject().dependsOn(
SUPPORT_LIB_ARTIFACT))) {
boolean useBuiltin = minSdk >= 16;
String message = useBuiltin ?
"Use `new LongSparseArray(...)` instead for better performance" :
"Use `new android.support.v4.util.LongSparseArray(...)` instead for better performance";
mContext.report(USE_SPARSE_ARRAY, node, mContext.getLocation(node),
message);
}
}
}
private void checkSparseArray(
@NonNull PsiNewExpression node,
@NonNull PsiJavaCodeReferenceElement reference) {
PsiType[] types = reference.getTypeParameters();
if (types.length == 1) {
String valueType = types[0].getCanonicalText();
if (valueType.equals(TYPE_INTEGER_WRAPPER)) {
mContext.report(USE_SPARSE_ARRAY, node, mContext.getLocation(node),
"Use `new SparseIntArray(...)` instead for better performance");
} else if (valueType.equals(TYPE_BOOLEAN_WRAPPER)) {
mContext.report(USE_SPARSE_ARRAY, node, mContext.getLocation(node),
"Use `new SparseBooleanArray(...)` instead for better performance");
}
}
}
}
private static String getUseValueOfErrorMessage(String typeName, String argument) {
// Keep in sync with {@link #getReplacedType} below
return String.format("Use `%1$s.valueOf(%2$s)` instead",
typeName.substring(typeName.lastIndexOf('.') + 1), argument);
}
/**
* For an error message for an {@link #USE_VALUE_OF} issue reported by this detector,
* returns the type being replaced. Intended to use for IDE quickfix implementations.
*/
@SuppressWarnings("unused") // Used by the IDE
@Nullable
public static String getReplacedType(@NonNull String message, @NonNull TextFormat format) {
message = format.toText(message);
int index = message.indexOf('.');
if (index != -1 && message.startsWith("Use ")) {
return message.substring(4, index);
}
return null;
}
/** Visitor which records variable names assigned into */
private static class AssignmentTracker extends JavaRecursiveElementVisitor {
private final Collection mVariables;
public AssignmentTracker(Collection variables) {
mVariables = variables;
}
@Override
public void visitAssignmentExpression(PsiAssignmentExpression node) {
super.visitAssignmentExpression(node);
PsiExpression left = node.getLExpression();
if (left instanceof PsiReferenceExpression) {
PsiReferenceExpression ref = (PsiReferenceExpression) left;
if (ref.getQualifier() instanceof PsiThisExpression ||
ref.getQualifier() instanceof PsiSuperExpression) {
mVariables.add(ref.getReferenceName());
} else {
mVariables.add(ref.getText());
}
} else if (left instanceof PsiIdentifier) {
mVariables.add(left.getText());
}
}
}
}