mediaview: Implement ArcDocumentsProviderRoot.

chrome/browser/chromeos/arc/fileapi/arc_documents_provider_document.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/chromeos/arc/fileapi/arc_documents_provider_document.h"
+
+#include <set>
+
+#include "base/memory/ptr_util.h"
+#include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
+#include "chrome/browser/chromeos/arc/fileapi/arc_documents_provider_util.h"
+#include "net/base/mime_util.h"
+
+namespace arc {
+
+ArcDocumentsProviderDocument::ArcDocumentsProviderDocument(
+    const std::string& document_id,
+    bool is_directory)
+    : document_id_(document_id),
+      is_directory_(is_directory),
+      children_(is_directory ? new ChildMap() : nullptr) {}
+
+ArcDocumentsProviderDocument::~ArcDocumentsProviderDocument() = default;
+
+// static
+ArcDocumentsProviderDocument* ArcDocumentsProviderDocument::CreateFromDocument(
+    const mojom::Document& document) {
+  return new ArcDocumentsProviderDocument(
+      document.document_id, document.mime_type == kAndroidDirectoryMimeType);
+}
+
+ArcDocumentsProviderDocument* ArcDocumentsProviderDocument::Lookup(
+    const base::FilePath& path) {
+  if (path.empty()) {

[Luis Héctor Chávez, 2016/12/15 02:40:31]

nit: elide braces for all the one-line if blocks.

[Shuhei Takahashi, 2016/12/15 06:50:57]

Done.

+    return this;
+  }
+  ArcDocumentsProviderDocument* current = this;
+  std::vector<base::FilePath::StringType> components;
+  path.GetComponents(&components);
+  for (const base::FilePath::StringType& component : components) {
+    if (!current->is_directory()) {
+      return nullptr;
+    }
+    auto iter = current->children_->find(component);
+    if (iter == current->children_->end()) {
+      return nullptr;
+    }
+    current = iter->second.get();
+  }
+  return current;
+}
+
+void ArcDocumentsProviderDocument::UpdateWithChildDocuments(
+    const std::vector<mojom::DocumentPtr>& children) {
+  DCHECK(is_directory_);
+
+  ChildMap& old_map = *children_;
+  ChildMap new_map;
+
+  std::set<mojom::Document*> processed;

[Luis Héctor Chávez, 2016/12/15 02:40:31]

How large do you think these maps/sets are going to get? Would it make sense to
use unordered_{set,map}?

[Shuhei Takahashi, 2016/12/15 06:50:57]

It is the number of files in a single directory, so it will be typically not
very large.

BTW is unordered_set efficient in terms of memory?

[Luis Héctor Chávez, 2016/12/15 23:54:26]

sort of. depends on the load factor. On 64-bit machines, overall it uses roughly
the same amount of memory as a std::set, but for some sizes it uses less, for
some it uses more. On 32-bit machines where the pointer overhead is smaller, the
proportion of time it uses more memory might be larger, though.

+
+  // If a document is in |old_map|, keep the mapping for them.
+  {
+    std::map<std::string, base::FilePath::StringType> reverse_old_map;
+    for (const auto& pair : old_map) {
+      reverse_old_map[pair.second->document_id()] = pair.first;
+    }
+    for (const mojom::DocumentPtr& child : children) {
+      auto iter = reverse_old_map.find(child->document_id);
+      if (iter != reverse_old_map.end()) {

[Luis Héctor Chávez, 2016/12/15 02:40:31]

nit:

if (iter == reverse_old_map.end())
  continue;

[Shuhei Takahashi, 2016/12/15 06:50:57]

Done.

+        new_map[iter->second].reset(CreateFromDocument(*child));
+        processed.insert(&*child);
+      }
+    }
+  }
+
+  // Process new documents without name conflicts.
+  std::map<base::FilePath::StringType, int> name_counters;

[Luis Héctor Chávez, 2016/12/15 02:40:31]

Can you also wrap this in a block to ensure |name_counters| is destroyed as soon
as it's not needed? (similar to what you did for |reverse_old_map|).

[Shuhei Takahashi, 2016/12/15 06:50:57]

Done.

+  for (const mojom::DocumentPtr& child : children) {
+    if (processed.count(&*child) > 0) {
+      continue;
+    }
+    name_counters[GetFileNameForDocument(child)] += 1;
+  }
+  for (const mojom::DocumentPtr& child : children) {
+    if (processed.count(&*child) > 0) {
+      continue;
+    }
+    base::FilePath::StringType filename = GetFileNameForDocument(child);
+    DCHECK(name_counters[filename] >= 1);
+    if (name_counters[filename] == 1 && new_map.count(filename) == 0) {
+      new_map[filename].reset(CreateFromDocument(*child));
+      processed.insert(&*child);
+    }
+  }
+
+  // Finally, deal with conflicts.
+  std::map<std::string, int> suffix_counters;
+  for (const mojom::DocumentPtr& child : children) {
+    if (processed.count(&*child) > 0) {
+      continue;
+    }
+
+    base::FilePath::StringType filename = GetFileNameForDocument(child);
+
+    if (new_map.count(filename) > 0) {
+      // Resolve a conflict by adding a suffix.
+      int& suffix_counter = suffix_counters[filename];
+      if (suffix_counter == 0) {
+        suffix_counter = 1;
+      }
+      while (true) {
+        std::string suffix = base::StringPrintf(" %d", suffix_counter);
+        ++suffix_counter;

[Luis Héctor Chávez, 2016/12/15 02:40:31]

Why not move this above L114? That way you don't need L110-L112.

[Shuhei Takahashi, 2016/12/15 06:50:57]

Sounds like a good idea.

+        base::FilePath::StringType new_filename =
+            base::FilePath(filename).InsertBeforeExtensionASCII(suffix).value();
+        if (new_map.count(new_filename) == 0) {
+          filename = new_filename;
+          break;
+        }
+      }
+    }
+
+    new_map[filename].reset(CreateFromDocument(*child));
+    processed.insert(&*child);
+  }
+
+  DCHECK_EQ(processed.size(), children.size());
+
+  old_map.swap(new_map);
+}
+
+// static
+base::FilePath::StringType ArcDocumentsProviderDocument::GetFileNameForDocument(
+    const mojom::DocumentPtr& document) {
+  base::FilePath::StringType filename = document->display_name;
+
+  // Replace path separators appearing in the file name.
+  // Chrome OS is POSIX and kSeparators is "/".
+  base::ReplaceChars(filename, base::FilePath::kSeparators, "_", &filename);
+
+  // Do not allow "." and "..", though this is very unlikely to happen.
+  if (filename == base::FilePath::kCurrentDirectory) {
+    filename = "dot";
+  } else if (filename == base::FilePath::kParentDirectory) {
+    filename = "dotdot";
+  }
+
+  // Since Chrome detects MIME type from file name extensions, we need to change
+  // the file name extension of the document if it does not match with its MIME
+  // type.
+  // For example, Audio Media Provider presents a music file with its title as
+  // the file name.
+  base::FilePath::StringType extension =
+      base::ToLowerASCII(base::FilePath(filename).Extension());
+  if (!extension.empty()) {
+    extension = extension.substr(1);  // Strip the leading dot.
+  }
+  std::vector<base::FilePath::StringType> possible_extensions;
+  net::GetExtensionsForMimeType(document->mime_type, &possible_extensions);
+  if (!possible_extensions.empty() &&
+      std::find(possible_extensions.begin(), possible_extensions.end(),
+                extension) == possible_extensions.end()) {
+    std::string new_extension;
+    if (!net::GetPreferredExtensionForMimeType(document->mime_type,
+                                               &new_extension)) {
+      new_extension = possible_extensions[0];
+    }
+    filename =
+        base::StringPrintf("%s.%s", filename.c_str(), new_extension.c_str());
+  }
+
+  return filename;
+}
+
+}  // namespace arc