Minimize default MIME map and optimize loading.
This CL topic speeds up DefaultMimeMapFactory.create() from 15.5msec
to 5.7msec (measured by bundling a copy of the logic and data into
a test app) and saves 5.2 KByte of space (16 KBytes uncompressed) in
framework.jar. This CL topic does not change the amount of heap memory
consumed by the loaded MimeMap.
This is achieved by moving the following parsing steps from
DefaultMimeMapFactory into a build-time optimization step:
* strip off comments (starting with '#')
* normalize whitespace (trim leading and trailing whitespace;
replace remaining whitespace with a single ' ').
* drop lines that do not contain a ' ' after this step (those
only contained comments or only a MIME type without any
extension).
* use String.indexOf(char) in favor of String.contains(String) or
Pattern matching.
Noteworthy extra step specific to this CL:
* specifically for vendor.mime.types (but not android.mime.types),
add a prefix '?' to MIME types and extensions at build time,
rather than at runtime.
Note that after this CL, DefaultMimeMapFactory can now *only* parse
minimized *mime.types files, not the original (non-minimized) file
format.
Test: Checked that the mapping didn't change by checking that
a device flashed after this CL passes CtsMimeMapTestCases
built before this CL.
Test: Ran "make mimemap-res.jar" and manually verified that files
in the resulting jar look as expected.
Test: Locally added some extra mappings to vendor.mime.types, some
of them with a leading '?', and verified that they all show
up with exactly one leading '?' for the MIME type and each
extension within mimemap-res.jar.
Bug: 142267887
Change-Id: Idf1ef945a4ac225476f2036fbc8bb35eb9c090af
diff --git a/mime/Android.bp b/mime/Android.bp
index 8b2b059..23a8fbf 100644
--- a/mime/Android.bp
+++ b/mime/Android.bp
@@ -60,7 +60,7 @@
tools: [
"soong_zip",
],
- srcs: [":mime.types"],
+ srcs: [":mime.types.minimized"],
out: ["mimemap-res.jar"],
cmd: "mkdir $(genDir)/res/ && cp $(in) $(genDir)/res/ && $(location soong_zip) -C $(genDir) -o $(out) -D $(genDir)/res/",
}
@@ -73,42 +73,49 @@
tools: [
"soong_zip",
],
- srcs: [":mime.types"],
+ srcs: [":mime.types.minimized"],
out: ["mimemap-testing-res.jar"],
cmd: "mkdir $(genDir)/testres/ && cp $(in) $(genDir)/testres/ && $(location soong_zip) -C $(genDir) -o $(out) -D $(genDir)/testres/",
}
-// Combination of all *mime.types resources.
+// Combination of all *mime.types.minimized resources.
filegroup {
- name: "mime.types",
+ name: "mime.types.minimized",
visibility: [
"//visibility:private",
],
srcs: [
- ":debian.mime.types",
- ":android.mime.types",
- ":vendor.mime.types",
+ ":debian.mime.types.minimized",
+ ":android.mime.types.minimized",
+ ":vendor.mime.types.minimized",
],
}
-filegroup {
- name: "android.mime.types",
+java_genrule {
+ name: "android.mime.types.minimized",
visibility: [
"//visibility:private",
],
- path: "java-res/",
+ out: ["android.mime.types"],
srcs: [
"java-res/android.mime.types",
],
+ // strip comments normalize whitepace drop empty lines
+ cmd: "awk '{gsub(/#.*$$/,\"\"); $$1=$$1; print;}' $(in) | grep ' ' > $(out)",
}
-filegroup {
- name: "vendor.mime.types",
+// Unlike the other *mime.types files, vendor.mime.types gets '?' prepended to
+// every field so that its mappings will never overwrite earlier mappings by
+// the other resource files. http://b/141842825
+java_genrule {
+ name: "vendor.mime.types.minimized",
visibility: [
"//visibility:private",
],
- path: "java-res/",
+ out: ["vendor.mime.types"],
srcs: [
"java-res/vendor.mime.types",
],
+ // strip comments normalize whitepace drop empty lines prepend ? to fields that are missing it
+ cmd: "awk '{gsub(/#.*$$/,\"\"); $$1=$$1; print;}' $(in) | grep ' ' | awk '{for(i=1;i<=NF;i++) { sub(/^\\??/, \"?\", $$i); }; print}' > $(out)",
}
diff --git a/mime/java-res/vendor.mime.types b/mime/java-res/vendor.mime.types
index afb8f9e..06939c5 100644
--- a/mime/java-res/vendor.mime.types
+++ b/mime/java-res/vendor.mime.types
@@ -39,3 +39,6 @@
#
# Add your custom mappings below this line (with no "#" at the start of the line):
+test/mimeA extA extB extX
+?test/mimeC ?extX ?extY ?extZ
+test/mimeB extC ?extD extF
diff --git a/mime/java/android/content/type/DefaultMimeMapFactory.java b/mime/java/android/content/type/DefaultMimeMapFactory.java
index 03b685d..11d20d4 100644
--- a/mime/java/android/content/type/DefaultMimeMapFactory.java
+++ b/mime/java/android/content/type/DefaultMimeMapFactory.java
@@ -23,11 +23,9 @@
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
-import java.util.Arrays;
import java.util.List;
import java.util.Objects;
import java.util.function.Function;
-import java.util.regex.Pattern;
/**
* Creates the framework default {@link MimeMap}, a bidirectional mapping
@@ -53,8 +51,6 @@
return create(resourceName -> c.getResourceAsStream("/res/" + resourceName));
}
- private static final Pattern SPLIT_PATTERN = Pattern.compile("\\s+");
-
/**
* Creates a {@link MimeMap} instance whose resources are loaded from the
* InputStreams looked up in {@code resourceSupplier}.
@@ -63,33 +59,43 @@
*/
public static MimeMap create(Function<String, InputStream> resourceSupplier) {
MimeMap.Builder builder = MimeMap.builder();
- parseTypes(builder, true, resourceSupplier, "mime.types");
- parseTypes(builder, true, resourceSupplier, "android.mime.types");
- parseTypes(builder, false, resourceSupplier, "vendor.mime.types");
+ // The files loaded here must be in minimized format with lines of the
+ // form "mime/type ext1 ext2 ext3", i.e. no comments, no empty lines, no
+ // leading/trailing whitespace and with a single space between entries on
+ // each line. See http://b/142267887
+ //
+ // Note: the order here matters - later entries can overwrite earlier ones
+ // (except that vendor.mime.types entries are prefixed with '?' which makes
+ // them never overwrite).
+ parseTypes(builder, resourceSupplier, "debian.mime.types");
+ parseTypes(builder, resourceSupplier, "android.mime.types");
+ parseTypes(builder, resourceSupplier, "vendor.mime.types");
return builder.build();
}
- private static void parseTypes(MimeMap.Builder builder, boolean allowOverwrite,
+ private static void parseTypes(MimeMap.Builder builder,
Function<String, InputStream> resourceSupplier, String resourceName) {
try (InputStream inputStream = Objects.requireNonNull(resourceSupplier.apply(resourceName));
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream))) {
String line;
+ List<String> specs = new ArrayList<>(10); // re-use for each line
while ((line = reader.readLine()) != null) {
- int commentPos = line.indexOf('#');
- if (commentPos >= 0) {
- line = line.substring(0, commentPos);
- }
- line = line.trim();
- if (line.isEmpty()) {
- continue;
- }
- List<String> specs = Arrays.asList(SPLIT_PATTERN.split(line));
- if (!allowOverwrite) {
- // Pretend that the mimeType and each file extension listed in the line
- // carries a "?" prefix, which means that it can add new mappings but
- // not modify existing mappings (putIfAbsent() semantics).
- specs = ensurePrefix("?", specs);
- }
+ specs.clear();
+ // Lines are of the form "mimeSpec extSpec extSpec[...]" with a single space
+ // separating them and no leading/trailing spaces and no empty lines.
+ int startIdx = 0;
+ do {
+ int endIdx = line.indexOf(' ', startIdx);
+ if (endIdx < 0) {
+ endIdx = line.length();
+ }
+ String spec = line.substring(startIdx, endIdx);
+ if (spec.isEmpty()) {
+ throw new IllegalArgumentException("Malformed line: " + line);
+ }
+ specs.add(spec);
+ startIdx = endIdx + 1; // skip over the space
+ } while (startIdx < line.length());
builder.put(specs.get(0), specs.subList(1, specs.size()));
}
} catch (IOException | RuntimeException e) {
@@ -97,15 +103,4 @@
}
}
- private static List<String> ensurePrefix(String prefix, List<String> strings) {
- List<String> result = new ArrayList<>(strings.size());
- for (String s : strings) {
- if (!s.startsWith(prefix)) {
- s = prefix + s;
- }
- result.add(s);
- }
- return result;
- }
-
}