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path: root/src/mongo/client/read_preference.cpp
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-rw-r--r--src/mongo/client/read_preference.cpp199
1 files changed, 93 insertions, 106 deletions
diff --git a/src/mongo/client/read_preference.cpp b/src/mongo/client/read_preference.cpp
index e088504fe15..2a1ee9d6420 100644
--- a/src/mongo/client/read_preference.cpp
+++ b/src/mongo/client/read_preference.cpp
@@ -44,19 +44,19 @@
namespace mongo {
namespace {
- const BSONArray tagsMatchesAll = BSON_ARRAY(BSONObj());
+const BSONArray tagsMatchesAll = BSON_ARRAY(BSONObj());
- const char kModeFieldName[] = "mode";
- const char kTagsFieldName[] = "tags";
+const char kModeFieldName[] = "mode";
+const char kTagsFieldName[] = "tags";
- const char kPrimaryOnly[] = "primary";
- const char kPrimaryPreferred[] = "primaryPreferred";
- const char kSecondaryOnly[] = "secondary";
- const char kSecondaryPreferred[] = "secondaryPreferred";
- const char kNearest[] = "nearest";
+const char kPrimaryOnly[] = "primary";
+const char kPrimaryPreferred[] = "primaryPreferred";
+const char kSecondaryOnly[] = "secondary";
+const char kSecondaryPreferred[] = "secondaryPreferred";
+const char kNearest[] = "nearest";
- StringData readPreferenceName(ReadPreference pref) {
- switch (pref) {
+StringData readPreferenceName(ReadPreference pref) {
+ switch (pref) {
case ReadPreference::PrimaryOnly:
return StringData(kPrimaryOnly);
case ReadPreference::PrimaryPreferred:
@@ -69,123 +69,110 @@ namespace {
return StringData(kNearest);
default:
MONGO_UNREACHABLE;
- }
}
-
- StatusWith<ReadPreference> parseReadPreferenceMode(StringData prefStr) {
- if (prefStr == kPrimaryOnly) {
- return ReadPreference::PrimaryOnly;
- }
- else if (prefStr == kPrimaryPreferred) {
- return ReadPreference::PrimaryPreferred;
- }
- else if (prefStr == kSecondaryOnly) {
- return ReadPreference::SecondaryOnly;
- }
- else if (prefStr == kSecondaryPreferred) {
- return ReadPreference::SecondaryPreferred;
- }
- else if (prefStr == kNearest) {
- return ReadPreference::Nearest;
- }
- return Status(ErrorCodes::FailedToParse,
- str::stream() << "Could not parse $readPreference mode '"
- << prefStr << "'. Only the modes '"
- << kPrimaryOnly << "', '"
- << kPrimaryPreferred << "', "
- << kSecondaryOnly << "', '"
- << kSecondaryPreferred << "', and '"
- << kNearest << "' are supported.");
+}
+
+StatusWith<ReadPreference> parseReadPreferenceMode(StringData prefStr) {
+ if (prefStr == kPrimaryOnly) {
+ return ReadPreference::PrimaryOnly;
+ } else if (prefStr == kPrimaryPreferred) {
+ return ReadPreference::PrimaryPreferred;
+ } else if (prefStr == kSecondaryOnly) {
+ return ReadPreference::SecondaryOnly;
+ } else if (prefStr == kSecondaryPreferred) {
+ return ReadPreference::SecondaryPreferred;
+ } else if (prefStr == kNearest) {
+ return ReadPreference::Nearest;
}
-
- // Slight kludge here: if we weren't passed a TagSet, we default to the empty
- // TagSet if ReadPreference is Primary, or the default (wildcard) TagSet otherwise.
- // This maintains compatibility with existing code, while preserving the ability to round
- // trip.
- TagSet defaultTagSetForMode(ReadPreference mode) {
- switch (mode) {
+ return Status(ErrorCodes::FailedToParse,
+ str::stream() << "Could not parse $readPreference mode '" << prefStr
+ << "'. Only the modes '" << kPrimaryOnly << "', '"
+ << kPrimaryPreferred << "', " << kSecondaryOnly << "', '"
+ << kSecondaryPreferred << "', and '" << kNearest
+ << "' are supported.");
+}
+
+// Slight kludge here: if we weren't passed a TagSet, we default to the empty
+// TagSet if ReadPreference is Primary, or the default (wildcard) TagSet otherwise.
+// This maintains compatibility with existing code, while preserving the ability to round
+// trip.
+TagSet defaultTagSetForMode(ReadPreference mode) {
+ switch (mode) {
case ReadPreference::PrimaryOnly:
return TagSet::primaryOnly();
default:
return TagSet();
- }
}
+}
} // namespace
- TagSet::TagSet() : _tags(tagsMatchesAll) {}
+TagSet::TagSet() : _tags(tagsMatchesAll) {}
- TagSet TagSet::primaryOnly() {
- return TagSet{BSONArray()};
- }
+TagSet TagSet::primaryOnly() {
+ return TagSet{BSONArray()};
+}
- ReadPreferenceSetting::ReadPreferenceSetting(ReadPreference pref, TagSet tags)
- : pref(std::move(pref))
- , tags(std::move(tags))
- {}
-
- StatusWith<ReadPreferenceSetting> ReadPreferenceSetting::fromBSON(const BSONObj& readPrefObj) {
- std::string modeStr;
- auto modeExtractStatus = bsonExtractStringField(readPrefObj,
- kModeFieldName,
- &modeStr);
- if (!modeExtractStatus.isOK()) {
- return modeExtractStatus;
- }
+ReadPreferenceSetting::ReadPreferenceSetting(ReadPreference pref, TagSet tags)
+ : pref(std::move(pref)), tags(std::move(tags)) {}
- ReadPreference mode;
- auto swReadPrefMode = parseReadPreferenceMode(modeStr);
- if (!swReadPrefMode.isOK()) {
- return swReadPrefMode.getStatus();
- }
- mode = std::move(swReadPrefMode.getValue());
-
- TagSet tags;
- BSONElement tagsElem;
- auto tagExtractStatus = bsonExtractTypedField(readPrefObj,
- kTagsFieldName,
- mongo::Array,
- &tagsElem);
- if (tagExtractStatus.isOK()) {
- tags = TagSet{BSONArray(tagsElem.Obj().getOwned())};
-
- // In accordance with the read preference spec, passing the default wildcard tagset
- // '[{}]' is the same as not passing a TagSet at all. Furthermore, passing an empty
- // TagSet with a non-primary ReadPreference is equivalent to passing the wildcard
- // ReadPreference.
- if (tags == TagSet() || tags == TagSet::primaryOnly()) {
- tags = defaultTagSetForMode(mode);
- }
-
- // If we are using a user supplied TagSet, check that it is compatible with
- // the readPreference mode.
- else if (ReadPreference::PrimaryOnly == mode && (tags != TagSet::primaryOnly())) {
- return Status(ErrorCodes::BadValue,
- "Only empty tags are allowed with primary read preference");
- }
- }
+StatusWith<ReadPreferenceSetting> ReadPreferenceSetting::fromBSON(const BSONObj& readPrefObj) {
+ std::string modeStr;
+ auto modeExtractStatus = bsonExtractStringField(readPrefObj, kModeFieldName, &modeStr);
+ if (!modeExtractStatus.isOK()) {
+ return modeExtractStatus;
+ }
- else if (ErrorCodes::NoSuchKey == tagExtractStatus) {
+ ReadPreference mode;
+ auto swReadPrefMode = parseReadPreferenceMode(modeStr);
+ if (!swReadPrefMode.isOK()) {
+ return swReadPrefMode.getStatus();
+ }
+ mode = std::move(swReadPrefMode.getValue());
+
+ TagSet tags;
+ BSONElement tagsElem;
+ auto tagExtractStatus =
+ bsonExtractTypedField(readPrefObj, kTagsFieldName, mongo::Array, &tagsElem);
+ if (tagExtractStatus.isOK()) {
+ tags = TagSet{BSONArray(tagsElem.Obj().getOwned())};
+
+ // In accordance with the read preference spec, passing the default wildcard tagset
+ // '[{}]' is the same as not passing a TagSet at all. Furthermore, passing an empty
+ // TagSet with a non-primary ReadPreference is equivalent to passing the wildcard
+ // ReadPreference.
+ if (tags == TagSet() || tags == TagSet::primaryOnly()) {
tags = defaultTagSetForMode(mode);
}
- else {
- return tagExtractStatus;
- }
- return ReadPreferenceSetting(mode, tags);
+ // If we are using a user supplied TagSet, check that it is compatible with
+ // the readPreference mode.
+ else if (ReadPreference::PrimaryOnly == mode && (tags != TagSet::primaryOnly())) {
+ return Status(ErrorCodes::BadValue,
+ "Only empty tags are allowed with primary read preference");
+ }
}
- BSONObj ReadPreferenceSetting::toBSON() const {
- BSONObjBuilder bob;
- bob.append(kModeFieldName, readPreferenceName(pref));
- if (tags != defaultTagSetForMode(pref)) {
- bob.append(kTagsFieldName, tags.getTagBSON());
- }
- return bob.obj();
+ else if (ErrorCodes::NoSuchKey == tagExtractStatus) {
+ tags = defaultTagSetForMode(mode);
+ } else {
+ return tagExtractStatus;
}
- std::string ReadPreferenceSetting::toString() const {
- return toBSON().toString();
+ return ReadPreferenceSetting(mode, tags);
+}
+
+BSONObj ReadPreferenceSetting::toBSON() const {
+ BSONObjBuilder bob;
+ bob.append(kModeFieldName, readPreferenceName(pref));
+ if (tags != defaultTagSetForMode(pref)) {
+ bob.append(kTagsFieldName, tags.getTagBSON());
}
+ return bob.obj();
+}
+
+std::string ReadPreferenceSetting::toString() const {
+ return toBSON().toString();
+}
} // namespace mongo
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