diff --git a/library/common/src/main/java/com/google/android/exoplayer2/util/Log.java b/library/common/src/main/java/com/google/android/exoplayer2/util/Log.java
index e5e6f88d4d..fd1b74ca6e 100644
--- a/library/common/src/main/java/com/google/android/exoplayer2/util/Log.java
+++ b/library/common/src/main/java/com/google/android/exoplayer2/util/Log.java
@@ -22,6 +22,7 @@ import java.lang.annotation.Documented;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.net.UnknownHostException;
+import org.checkerframework.dataflow.qual.Pure;
 
 /** Wrapper around {@link android.util.Log} which allows to set the log level. */
 public final class Log {
@@ -51,11 +52,13 @@ public final class Log {
   private Log() {}
 
   /** Returns current {@link LogLevel} for ExoPlayer logcat logging. */
+  @Pure
   public static @LogLevel int getLogLevel() {
     return logLevel;
   }
 
   /** Returns whether stack traces of {@link Throwable}s will be logged to logcat. */
+  @Pure
   public boolean getLogStackTraces() {
     return logStackTraces;
   }
@@ -80,6 +83,7 @@ public final class Log {
   }
 
   /** @see android.util.Log#d(String, String) */
+  @Pure
   public static void d(String tag, String message) {
     if (logLevel == LOG_LEVEL_ALL) {
       android.util.Log.d(tag, message);
@@ -87,11 +91,13 @@ public final class Log {
   }
 
   /** @see android.util.Log#d(String, String, Throwable) */
+  @Pure
   public static void d(String tag, String message, @Nullable Throwable throwable) {
     d(tag, appendThrowableString(message, throwable));
   }
 
   /** @see android.util.Log#i(String, String) */
+  @Pure
   public static void i(String tag, String message) {
     if (logLevel <= LOG_LEVEL_INFO) {
       android.util.Log.i(tag, message);
@@ -99,11 +105,13 @@ public final class Log {
   }
 
   /** @see android.util.Log#i(String, String, Throwable) */
+  @Pure
   public static void i(String tag, String message, @Nullable Throwable throwable) {
     i(tag, appendThrowableString(message, throwable));
   }
 
   /** @see android.util.Log#w(String, String) */
+  @Pure
   public static void w(String tag, String message) {
     if (logLevel <= LOG_LEVEL_WARNING) {
       android.util.Log.w(tag, message);
@@ -111,11 +119,13 @@ public final class Log {
   }
 
   /** @see android.util.Log#w(String, String, Throwable) */
+  @Pure
   public static void w(String tag, String message, @Nullable Throwable throwable) {
     w(tag, appendThrowableString(message, throwable));
   }
 
   /** @see android.util.Log#e(String, String) */
+  @Pure
   public static void e(String tag, String message) {
     if (logLevel <= LOG_LEVEL_ERROR) {
       android.util.Log.e(tag, message);
@@ -123,6 +133,7 @@ public final class Log {
   }
 
   /** @see android.util.Log#e(String, String, Throwable) */
+  @Pure
   public static void e(String tag, String message, @Nullable Throwable throwable) {
     e(tag, appendThrowableString(message, throwable));
   }
@@ -139,6 +150,7 @@ public final class Log {
    * @return The string representation of the {@link Throwable}.
    */
   @Nullable
+  @Pure
   public static String getThrowableString(@Nullable Throwable throwable) {
     if (throwable == null) {
       return null;
@@ -157,6 +169,7 @@ public final class Log {
     }
   }
 
+  @Pure
   private static String appendThrowableString(String message, @Nullable Throwable throwable) {
     @Nullable String throwableString = getThrowableString(throwable);
     if (!TextUtils.isEmpty(throwableString)) {
@@ -165,6 +178,7 @@ public final class Log {
     return message;
   }
 
+  @Pure
   private static boolean isCausedByUnknownHostException(@Nullable Throwable throwable) {
     while (throwable != null) {
       if (throwable instanceof UnknownHostException) {