src/couchdb/couch_db.hrl

% 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.

-define(LOCAL_DOC_PREFIX, "_local/").
-define(DESIGN_DOC_PREFIX0, "_design").
-define(DESIGN_DOC_PREFIX, "_design/").
-define(DEFAULT_COMPRESSION, snappy).

-define(MIN_STR, <<"">>).
-define(MAX_STR, <<255>>). % illegal utf string

% the lowest possible database sequence number
-define(LOWEST_SEQ, 0).

-define(REWRITE_COUNT, couch_rewrite_count).

-define(JSON_ENCODE(V), ejson:encode(V)).
-define(JSON_DECODE(V), ejson:decode(V)).

-define(b2l(V), binary_to_list(V)).
-define(l2b(V), list_to_binary(V)).
-define(term_to_bin(T), term_to_binary(T, [{minor_version, 1}])).
-define(term_size(T),
    try
        erlang:external_size(T)
    catch _:_ ->
        byte_size(?term_to_bin(T))
    end).

-define(DEFAULT_ATTACHMENT_CONTENT_TYPE, <<"application/octet-stream">>).

-define(LOG_DEBUG(Format, Args),
    case couch_log:debug_on(?MODULE) of
        true ->
            couch_log:debug(Format, Args);
        false -> ok
    end).

-define(LOG_INFO(Format, Args),
    case couch_log:info_on(?MODULE) of
        true ->
            couch_log:info(Format, Args);
        false -> ok
    end).

-define(LOG_WARN(Format, Args),
    case couch_log:warn_on(?MODULE) of
        true ->
            couch_log:warn(Format, Args);
        false -> ok
    end).

-define(LOG_ERROR(Format, Args), couch_log:error(Format, Args)).

% Tree::term() is really a tree(), but we don't want to require R13B04 yet
-type branch() :: {Key::term(), Value::term(), Tree::term()}.
-type path() :: {Start::pos_integer(), branch()}.
-type tree() :: [branch()]. % sorted by key

-record(rev_info,
    {
    rev,
    seq = 0,
    deleted = false,
    body_sp = nil % stream pointer
    }).

-record(doc_info,
    {
    id = <<"">>,
    high_seq = 0,
    revs = [] % rev_info
    }).

-record(full_doc_info,
    {id = <<"">>,
    update_seq = 0,
    deleted = false,
    rev_tree = [],
    leafs_size = 0
    }).

-record(httpd,
    {mochi_req,
    peer,
    method,
    requested_path_parts,
    path_parts,
    db_url_handlers,
    user_ctx,
    req_body = undefined,
    design_url_handlers,
    auth,
    default_fun,
    url_handlers
    }).


-record(doc,
    {
    id = <<"">>,
    revs = {0, []},

    % the json body object.
    body = {[]},

    atts = [], % attachments

    deleted = false,

    % key/value tuple of meta information, provided when using special options:
    % couch_db:open_doc(Db, Id, Options).
    meta = []
    }).


-record(att,
    {
    name,
    type,
    att_len,
    disk_len, % length of the attachment in its identity form
              % (that is, without a content encoding applied to it)
              % differs from att_len when encoding /= identity
    md5= <<>>,
    revpos=0,
    data,
    encoding=identity % currently supported values are:
                      %     identity, gzip
                      % additional values to support in the future:
                      %     deflate, compress
    }).


-record(user_ctx,
    {
    name=null,
    roles=[],
    handler
    }).

% This should be updated anytime a header change happens that requires more
% than filling in new defaults.
%
% As long the changes are limited to new header fields (with inline
% defaults) added to the end of the record, then there is no need to increment
% the disk revision number.
%
% if the disk revision is incremented, then new upgrade logic will need to be
% added to couch_db_updater:init_db.

-define(LATEST_DISK_VERSION, 6).

-record(db_header,
    {disk_version = ?LATEST_DISK_VERSION,
     update_seq = 0,
     unused = 0,
     fulldocinfo_by_id_btree_state = nil,
     docinfo_by_seq_btree_state = nil,
     local_docs_btree_state = nil,
     purge_seq = 0,
     purged_docs = nil,
     security_ptr = nil,
     revs_limit = 1000
    }).

-record(db,
    {main_pid = nil,
    update_pid = nil,
    compactor_pid = nil,
    instance_start_time, % number of microsecs since jan 1 1970 as a binary string
    fd,
    updater_fd,
    fd_ref_counter,
    header = #db_header{},
    committed_update_seq,
    fulldocinfo_by_id_btree,
    docinfo_by_seq_btree,
    local_docs_btree,
    update_seq,
    name,
    filepath,
    validate_doc_funs = [],
    security = [],
    security_ptr = nil,
    user_ctx = #user_ctx{},
    waiting_delayed_commit = nil,
    revs_limit = 1000,
    fsync_options = [],
    options = [],
    compression,
    before_doc_update = nil, % nil | fun(Doc, Db) -> NewDoc
    after_doc_read = nil     % nil | fun(Doc, Db) -> NewDoc
    }).


-record(view_query_args, {
    start_key,
    end_key,
    start_docid = ?MIN_STR,
    end_docid = ?MAX_STR,

    direction = fwd,
    inclusive_end=true, % aka a closed-interval

    limit = 10000000000, % Huge number to simplify logic
    skip = 0,

    group_level = 0,

    view_type = nil,
    include_docs = false,
    doc_options = [],
    conflicts = false,
    stale = false,
    multi_get = false,
    callback = nil,
    list = nil
}).

-record(view_fold_helper_funs, {
    reduce_count,
    passed_end,
    start_response,
    send_row
}).

-record(reduce_fold_helper_funs, {
    start_response,
    send_row
}).

-record(extern_resp_args, {
    code = 200,
    stop = false,
    data = <<>>,
    ctype = "application/json",
    headers = [],
    json = nil
}).

-record(index_header,
    {seq=0,
    purge_seq=0,
    id_btree_state=nil,
    view_states=nil
    }).

% small value used in revision trees to indicate the revision isn't stored
-define(REV_MISSING, []).

-record(changes_args, {
    feed = "normal",
    dir = fwd,
    since = 0,
    limit = 1000000000000000,
    style = main_only,
    heartbeat,
    timeout,
    filter = "",
    filter_fun,
    filter_args = [],
    include_docs = false,
    doc_options = [],
    conflicts = false,
    db_open_options = []
}).

-record(btree, {
    fd,
    root,
    extract_kv = fun({_Key, _Value} = KV) -> KV end,
    assemble_kv = fun(Key, Value) -> {Key, Value} end,
    less = fun(A, B) -> A < B end,
    reduce = nil,
    compression = ?DEFAULT_COMPRESSION
}).